Displacement filter apparatus and method

ABSTRACT

A method and apparatus for filtering a slurry utilizing a displacement filtering principle. The filter apparatus desirably includes an inner filter and an outer filter. Both the inner and outer filters are preferably substantially annular in shape and positioned concentrically with respect to each other. A particulate collection volume is at least partially defined between the inner and outer filter. The method includes directing a flow of slurry into the particulate collection volume under sufficient pressure to force fluid within the particulate collection volume through one of the inner and outer filters and any particulate matter blocking a filtering surface of the inner and outer filters.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to the filtering of particulatematter from a slurry. More specifically, the present invention relatesto the filtering of slurries having a relatively high particulatecontent utilizing a displacement filtering principle.

[0003] 2. Description of the Related Art

[0004] Separating the liquid and solid components of a liquid-solidmixture, or slurry, is a necessary or desirable process in manyindustries. In many filtering applications, the slurry is a wasteproduct and it is desirable to separate the solid and liquid matter anddispose of them separately. Often, the solid component may be ahazardous material and the liquid component may be reused or recycled.In other applications, the liquid component may be the final product,such as in the wine industry, for example. In this application, thesolid component is desirably separated from the liquid to provide purityand clarity to the wine.

[0005] One method for separating liquids and solids is known as surfacefiltering. In a surface filtering process, the liquid-solid mixture ispassed through a filter element under the influence of gravity or arelatively low pressure. The liquid component of the mixture passesthrough the filter element while the solid component is retainedprimarily on the surface of the filter element. However, with this typeof filtering process, once the surface of the filter element issubstantially covered with solid particulate matter, liquid is no longerable to pass through. Thus, surface filter processes are useful only forfiltering slurries having a low concentration of solid matter.

[0006] A method more suitable for filtering slurries having a relativelyhigh concentration of solids utilizes an apparatus referred to as a tubepress. A tube press typically includes a cylindrical tube with a smallerdiameter cylindrical filter concentrically positioned therein. Aflexible bladder is positioned adjacent the inner surface of the tube. Afixed volume of slurry is introduced into a space between the tube andthe inner filter and an inlet to the tube is closed and sealed.Hydraulic fluid is forced under pressure into a gap between the tube andthe bladder to expand the bladder. The expansion of the bladder forcesthe liquid within the tube through the filter, while the solid matter isretained within the tube. However, this method of filtering isinefficient because the tube press only processes a fixed volume ofslurry during a filtering cycle. As a result, the solid matter remainingat the end of the filter cycle is typically only a small percentage ofthe total available volume defined between the tube and the filter.Additionally, solids must be removed and the filter cleaned between eachfiltering cycle. Consequently, this process is typically used only inapplications where the slurry has an extremely high concentration ofsolids or in applications where an extremely dry particulate “cake” isdesired.

[0007] Another method of filtering slurries having relatively highconcentrations of solid matter uses an apparatus known as a filterpress, which operates under a displacement filtering principle. A filterpress utilizes a series of filter plates placed adjacent to one another.A space is defined between each pair of the filter plates and each spaceis lined with filter media. Typically, each of the filter plates includea central aperture. Thus, all of the spaces between each pair of platescommunicate with one another. An inlet is provided to introduce slurryinto the interconnected spaces on an upstream side of the filter media.One or more outlets communicate with each space on a downstream side ofthe filter element.

[0008] Slurry is introduced through the inlet to fill all of theindividual spaces between the filter plates. Once the spaces are filled,the delivery pressure of the incoming slurry is increased such that theliquid component is displaced through the filter media and the solidparticulate matter is retained within the spaces upstream from thefilter media. The filtered liquid, or filtrate, moves to the outlet(s),where it is discharged. The filter cycle continues until each of thespaces is substantially filled with particulate matter. Thus, the filterpress utilizes substantially the entire volume of the spaces rather thanrelying on the surface area of the filter media, as is the case withsurface filtering methods. However, due to the large forces generated bythe pressure within the spaces, a large and costly support frame andhydraulic system is necessary to hold the plates together during thefilter cycle. In addition, the solid particulate “cake” remaining ineach individual space after the filter cycle must be removed inpreparation for a subsequent filter cycle. Because as many as a hundredor more individual plates may be used, the cleaning process is verytime-consuming and results in excessive down-time in which the filterpress is not utilized. Also, due to the provision of multiple plates,which must be separated from one another to allow the particulate matterto be discharged and the filter media to be cleaned, fully automatedfiltering systems are often prohibitively expensive.

SUMMARY OF THE INVENTION

[0009] Advantageously, preferred embodiments and methods utilize adisplacement principle for filtering slurries having a relatively highconcentration of solids without the above-described disadvantagesassociated with the filter press. Preferred embodiments utilize asimplified structural arrangement to permit a less costly supportstructure and closure system to be provided. In addition, preferredembodiments drastically reduce the time necessary for dischargingparticulate matter and preparing the filter for subsequent use.Furthermore, preferred embodiments are desirably capable of beingequipped with simplified and cost-effective automated cleaning systemsto preferably completely eliminate the need for an operator and furtherreduce the down-time of the filter apparatus.

[0010] A preferred embodiment is a filter apparatus including a firstoutlet and a second outlet. The filter additionally includes an annularinner filter defining an external surface, an internal surface and aninternal cavity. The first outlet is located downstream from theinternal surface of the inner filter. An outer filter surrounds theinner filter and defines an internal surface and an external surface.The inner filter and the outer filter define an annular particulatecollection volume. The second outlet is located downstream from theexternal surface of the outer filter. The filter includes an inletdirecting fluid into the particulate collection volume before the fluidpasses through either the inner filter or the outer filter. A pressuresource is positioned upstream from the inlet and directs pressurethrough the inlet to force fluid within the particulate collectionvolume through the inner filter to the first outlet and through theouter filter to the second outlet.

[0011] A preferred embodiment is a filter apparatus for dewatering aslurry including a pressure vessel having a first end, a second end, anda one-piece, annular side wall portion. The side wall portion has aninternal surface generally defining an internal space and one of thefirst end and the second end defines an opening to permit access to theinternal space. A closure is sized and shaped for selectively closingthe opening. The pressure vessel and the closure are configured towithstand a pressure of at least 25 psi in the internal space when theopening is closed. An annular inner filter defines an external surfaceand an internal cavity, the internal cavity at least partially defininga first outlet space. A substantial portion of the inner filter whichforms the external surface includes a first filter media. An outerfilter surrounds the inner filter and defines an internal surface facingthe external surface. A substantial portion of the outer filter whichforms the internal surface includes a second filter media. The firstfilter media and the second filter media comprise a woven material or amaterial configured to retain a particulate size greater than or equalto about 0.25 microns. The first and second filter media define anannular particulate collection volume between them. The outer filter andthe internal surface of the vessel define a second outlet space betweenthem. An inlet communicates with the internal space and is configured todirect a slurry into the particulate collection volume before the slurrypasses through either the inner filter or the outer filter. An outletcommunicates with the internal space and is in fluid communication withboth the first outlet space and the second outlet space. A pressuresource is upstream from the inlet and pressure from the pressure sourceis directable through the inlet to force a fluid component of a slurrywithin the particulate collection volume through the inner filter to thefirst outlet space and through the outer filter to the second outletspace. The first and second filter media retain a solid component of aslurry within the particulate collection volume to form a particulatecake. The opening is sized and shaped to permit a particulate cakewithin the particulate collection volume to be removed through theopening.

[0012] A preferred embodiment is a filter apparatus for dewatering aslurry including a pressure vessel having a first end, a second end, anda one-piece, annular side wall portion. The side wall portion has aninternal surface generally defining an internal space. Either the firstend or the second end defines an opening to permit access to theinternal space. A closure is sized and shaped for selectively closingthe opening. An annular inner filter defines an external surface and aninternal cavity, which at least partially defines a first outlet space.A substantial portion of the inner filter which forms the externalsurface includes a first filter media. An outer filter surrounds theinner filter and defines an internal surface facing the externalsurface. The internal surface and the external surface are substantiallyparallel and a substantial portion of the outer filter which forms theinternal surface includes a second filter media. The first filter mediaand the second filter media comprise either a woven material or amaterial configured to retain a particulate size greater than or equalto about 0.25 microns. The first and second filter media define anannular particulate collection volume therebetween and the outer filterand the internal surface of the vessel define a second outlet spacetherebetween. An inlet communicates with the internal space and isconfigured to direct a slurry into the particulate collection volumebefore the slurry passes through either of the inner filter and theouter filter. An outlet communicates with the internal space and is influid communication with the first outlet space and the second outletspace. A pressure source is upstream from the inlet and pressure fromthe pressure source is directable through the inlet to force a fluidcomponent of a slurry within the particulate collection volume throughthe inner filter to the first outlet space and through the outer filterto the second outlet space. The first and second filter media retain asolid component of a slurry within the particulate collection volume toform a particulate cake. The opening is sized and shaped to permit aparticulate cake within the particulate collection volume to be removedthrough the opening. The pressure source produces a first fluid pressureupstream from the particulate collection volume and a second fluidpressure downstream from the particulate collection volume. Thedifference between the first fluid pressure and the second fluidpressure define a pressure differential. The filter apparatus isconfigured to withstand operating pressure differentials of at least 25psi.

[0013] A preferred embodiment is a filter apparatus for filtering aslurry including a pressure vessel having a first end, a second end andan annular wall. A support portion is configured to secure the pressurevessel in a location. The wall of the pressure vessel includes a firstportion between the support and the first end or the second end of thevessel. The first portion of the wall is capable of providing sufficientresistance to gravity acting on the first portion of the wall tomaintain the structural integrity of the first portion of the wall. Anannular inner filter defines an external surface and an internal cavity,which at least partially defines a first outlet space. A substantialportion of the inner filter which forms the external surface includes afirst filter media. An outer filter surrounds the inner filter anddefines an internal surface facing the external surface. A substantialportion of the outer filter which forms the internal surface includes asecond filter media. The first filter media and the second filter mediacomprise either a woven material or a material configured to retain aparticulate size greater than or equal to about 0.25 microns. The firstand second filter media define an annular particulate collection volumetherebetween and the outer filter and the internal surface of the vesseldefining a second outlet space therebetween. An inlet communicates withthe internal space and directs the slurry into the particulatecollection volume before passing through either of the inner filter andthe outer filter. An outlet communicates with the internal space and isin fluid communication with the first outlet space and the second outletspace. A pressure source is upstream from the inlet and pressure fromthe pressure source is directable through the inlet to force a fluidcomponent of a slurry within the particulate collection volume throughthe inner filter to the first outlet space and through the outer filterto the second outlet space. The first and second filter media retain asolid component of a slurry within the particulate collection volume toform a particulate cake.

[0014] A preferred embodiment is a filter apparatus as recited in thepreceding paragraph and additionally comprising a second support portionconfigured to secure the pressure vessel in a location. The wall of thepressure vessel including a second portion between the first support andthe second support. The second portion of the wall being capable ofproviding sufficient resistance to gravity acting on the second portionof the wall to maintain the structural integrity of the second portionof the wall. A preferred embodiment is a filter apparatus as in thepreceding paragraph, wherein the inner filter and the outer filtercomprise a filter assembly having a first end and a second. The filterapparatus further comprising a first filter assembly support and asecond filter assembly support. The filter assembly includes a portionbetween the first filter assembly support and the second filter assemblysupport. The portion of the filter assembly being capable of providingsufficient resistance to gravity acting on the filter assembly tomaintain the structural integrity of the filter assembly.

[0015] A preferred embodiment is a filter apparatus for dewatering aslurry, including a pressure vessel having a first end, a second end,and a one-piece, annular side wall portion. The side wall portion has aninternal surface generally defining an internal space. One of the firstend and the second end defines an opening to permit access to theinternal space and a closure is sized and shaped for selectively closingthe opening. The pressure vessel and the closure are configured towithstand a pressure of at least 25 psi in the internal space when theopening is closed. The apparatus includes at least one filter assemblycomprising a first filter and a second filter. The first filter definesa first surface and at least partially defines a first outlet space. Asubstantial portion of the first filter which forms the first surfacecomprises a first filter media. The second filter defines a secondsurface facing the first surface and at least partially defines a secondoutlet space. A substantial portion of the second filter which forms thesecond surface comprises a second filter media. The first and secondfilter media define a particulate collection volume therebetween. Aninlet communicates with the internal space and is configured to direct aslurry into the particulate collection volume before passing througheither of the first filter and the second filter. An outlet communicateswith the internal space and is in fluid communication with the firstoutlet space and the second outlet space. A pressure source is disposedupstream from the inlet, wherein pressure from the pressure source isdirectable through the inlet to force a fluid component of a slurrywithin the particulate collection volume through the first filter to thefirst outlet space and through the second filter to the second outletspace. The first and second filter media retain a solid component of aslurry within the particulate collection volume to form a particulatecake. The opening is sized and shaped to permit a particulate cakewithin the particulate collection volume to be removed through theopening. The apparatus also includes a scraper sized and shaped toextend substantially from the first filter media to the second filtermedia. The scraper is movable from a first end of the particulatecollection volume toward a second end of the particulate collectionvolume to remove particulate cake from the particulate collectionvolume.

[0016] A preferred embodiment is a filter apparatus for dewatering aslurry, comprising a pressure vessel having a first end, a second end,and a one-piece, annular side wall portion. The side wall portion has aninternal surface generally defining an internal space. One of the firstend and the second end define an opening to permit access to theinternal space. A closure is sized and shaped for selectively closingthe opening. The apparatus includes at least one filter assemblycomprising a first filter and a second filter. The first filter define afirst surface and at least partially defines a first outlet space. Asubstantial portion of the first filter which forms the first surfacecomprises a first filter media. The second filter defines a secondsurface facing the first surface and at least partially defines a secondoutlet space. The first surface and the second surface are substantiallyparallel and a substantial portion of the second filter which forms thesecond surface comprises a second filter media. The first and secondfilter media define a particulate collection volume therebetween. Aninlet communicates with the internal space and is configured to direct aslurry into the particulate collection volume before passing througheither of the first filter and the second filter. An outlet communicateswith the internal space and is in fluid communication with the firstoutlet space and the second outlet space. A pressure source is disposedupstream from the inlet, wherein pressure from the pressure source isdirectable through the inlet to force a fluid component of a slurrywithin the particulate collection volume through the first filter to thefirst outlet space and through the second filter to the second outletspace. The first and second filter media retain a solid component of aslurry within the particulate collection volume to form a particulatecake. The opening is sized and shaped to permit a particulate cakewithin the particulate collection volume to be removed through theopening. The pressure source produces a first fluid pressure upstreamfrom the particulate collection volume and a second fluid pressuredownstream from the particulate collection volume. The differencebetween the first fluid pressure and the second fluid pressure defines apressure differential. The filter apparatus is configured to withstandoperating pressure differentials of at least 25 psi. The apparatus alsoincludes a scraper sized and shaped to extend substantially from thefirst filter media to the second filter media, the scraper being movablefrom a first end of the particulate collection volume toward a secondend of the particulate collection volume to remove particulate cake fromthe particulate collection volume.

[0017] A preferred embodiment is a filter apparatus for filtering aslurry, comprising a pressure vessel having a first end, a second endand an annular wall. A support portion is configured to secure thepressure vessel in a location. The wall of the pressure vessel includesa first portion between the support and one of the first end and thesecond end of the vessel, which is capable of providing sufficientresistance to gravity acting on the first portion of the wall tomaintain the structural integrity of the first portion of the wall. Theapparatus includes at least one filter assembly having a first filterand a second filter. The first filter defines a first surface and atleast partially defines a first outlet space. A substantial portion ofthe first filter which forms the first surface comprises a first filtermedia. The second filter defines a second surface facing the firstsurface and at least partially defines a second outlet space. Asubstantial portion of the second filter which forms the second surfacecomprises a second filter media, the first and second filter mediadefining a particulate collection volume therebetween. An inletcommunicates with the internal space and directs the slurry into theparticulate collection volume before the slurry passes through either ofthe first filter or second filter. An outlet communicates with theinternal space and is in fluid communication with the first outlet spaceand the second outlet space. A pressure source is disposed upstream fromthe inlet, wherein pressure from the pressure source is directablethrough the inlet to force a fluid component of a slurry within theparticulate collection volume through the first filter to the firstoutlet space and through the second filter to the second outlet space.The first and second filter media retain a solid component of a slurrywithin the particulate collection volume to form a particulate cake. Ascraper is sized and shaped to extend substantially from the firstfilter media to the second filter media. The scraper is movable from afirst end of the particulate collection volume toward a second end ofthe particulate collection volume to remove particulate cake from theparticulate collection volume.

[0018] A preferred method of separating particulate matter from a slurryincludes providing a first outlet and providing a particulate collectionvolume. The method additionally includes providing a first annularfilter separating the first outlet from the particulate collectionvolume. A flow of the slurry is directed into the particulate collectionvolume under sufficient pressure to force fluid through the firstannular filter and any of the particulate matter blocking a filteringsurface of the first annular filter to substantially fill theparticulate collection volume with particulate.

[0019] A preferred embodiment is a filter apparatus including a pressurevessel defining an interior space. The filter apparatus includes a firstfilter defining a first surface and a second filter defining a secondsurface. The second surface faces the first surface. The first filterand the second filter at least partially define a particulate collectionvolume therebetween. An inlet directs fluid into the particulatecollection volume before the fluid passes through either the firstfilter or the second filter. At least one outlet is located downstreamfrom at least one of the first surface and the second surface. Apressure source is positioned upstream from the inlet and directspressure through the inlet to force fluid within the collection volumethrough the first filter and the second filter to the at least oneoutlet.

[0020] A preferred embodiment is a filter apparatus having an annularinner filter defining an internal cavity and an outer filter surroundingthe inner filter. The inner filter and the outer filter define anannular particulate collection volume when the filter apparatus is in aclosed position. The inner filter and the outer filter are movableaxially with respect to one another to define an open position whereinparticulate may be emptied from the filter apparatus. The filterincludes an inlet and an outlet. The outlet is located downstream fromthe particulate collection volume and the inlet directs fluid into theparticulate collection volume before the fluid passes through either theinner filter or the outer filter. The filter also includes a drivehaving a portion which exerts force on at least one of the inner filterand the outer filter to move the filter apparatus between the openposition and the closed position.

[0021] A preferred embodiment is a method of separating particulatematter from a slurry including providing a filter apparatus comprisingan annular inner filter and an outer filter surrounding the innerfilter. The inner filter and the outer filter define an annularparticulate collection volume between them. The filter apparatus furtherincludes an outlet located downstream from the particulate collectionvolume and an inlet directing fluid into the particulate collectionvolume before the fluid passes through either the inner filter or theouter filter. The method further includes initiating a filtering cyclecomprising directing a flow of the slurry into the particulatecollection volume under sufficient pressure to force fluid through theinner and outer filters and any of the particulate matter blocking afiltering surface of the inner and outer filters to substantially fillthe particulate collection volume and initiating a drive to move theinner filter and the outer filter axially with respect to one anotherupon completion of the filtering cycle to empty particulate from theparticulate collection volume.

[0022] A preferred embodiment is a filter apparatus including an annularinner filter defining an internal cavity and an outer filter surroundingthe inner filter. The inner filter and the outer filter define anannular particulate collection volume when the filter apparatus is in aclosed position. The inner filter and the outer filter are movableaxially with respect to one another to define an open position whereinparticulate may be emptied from the filter apparatus. An outlet islocated downstream from the particulate collection volume and an inletdirects fluid into the particulate collection volume before the fluidpasses through either the inner filter or the outer filter. The filterincludes means for moving the filter apparatus between the open positionand the closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other features of the preferred filters and methodswill be described with reference to drawings of the preferredembodiments. These embodiments are merely intended to illustrate, ratherthan limit, the present invention. The drawings contain seventeenfigures:

[0024]FIG. 1 is a partial schematic, perspective view of a preferredfilter apparatus. A portion of several components have been cut away toillustrate internal features of the filter, including an inner filterand an outer filter;

[0025]FIG. 2 is an enlarged cross section view of the portion of thefilter apparatus of FIG. 1 within the circle labeled 2 in FIG. 1;

[0026]FIG. 3 is an enlarged cross section view of the portion of thefilter apparatus of FIG. 1 within the circle labeled 3 in FIG. 1;

[0027]FIG. 4 is a partial schematic, perspective view of an alternativeembodiment of a filter apparatus. A portion of several components havebeen cut away to illustrate internal components and features of thefilter, including an inner filter and an outer filter;

[0028]FIG. 5 illustrates the filter apparatus of FIG. 3 having the innerfilter partially extracted from the filter apparatus to allowparticulate to be discharged;

[0029]FIG. 6A is a cross section view of an alternative filter assemblywherein the inner and outer filters have a corrugated shape;

[0030]FIG. 6B is a schematic cross section of an alternative filterassembly wherein multiple sets of filters are provided in a concentricarrangement;

[0031]FIG. 6C is a schematic cross section of an alternative filterassembly having a plurality of radially extending filters;

[0032]FIG. 6D is a schematic cross section of an alternative filterassembly having a plurality of linear filters;

[0033]FIG. 7 is a perspective view of an automatic embodiment of afilter assembly. Portions of the filter assembly are cutaway toillustrate various internal components;

[0034]FIG. 8 is a cross sectional view of a portion of the filterassembly of FIG. 7, illustrating a mechanical squeeze assembly;

[0035]FIG. 9 is a plan view of a portion of the filter assembly of FIG.7, taken along view line 9-9 of FIG. 8;

[0036]FIG. 10 is a schematic cross sectional view of the filter assemblyof FIG. 7 in a particulate cake discharge mode;

[0037]FIG. 11 is a schematic cross sectional view of the filter assemblyof FIG. 7 in a filter media wash mode;

[0038]FIG. 12 is a perspective view of a modification of the automaticfilter of FIG. 7 utilizing a pair of interconnected filters. In theembodiment of FIG. 12, the vessel is lifted from the inner filter by atelescoping rod arrangement to permit discharge of particulate cake;

[0039]FIG. 13 is a cross sectional view of a connection assembly betweena vessel portion and an inner filter portion of the filter of FIG. 12;

[0040]FIG. 14 is a perspective view of an alternative arrangement of anautomatic system utilizing a pair of filters;

[0041]FIG. 15 is a perspective view of an automatic filter assemblyutilizing an alternative embodiment of a filter closure arrangement;

[0042]FIG. 16 is an enlarged perspective view of a drive wheel of thefilter closure arrangement of FIG. 15; and

[0043]FIG. 17 is an enlarged perspective view of a idler wheel of thefilter closure arrangement of FIG. 15.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0044] FIGS. 1-3 illustrate a preferred embodiment of a filter apparatus10, generally referred to as a “filter” herein. The filter 10 includes asubstantially tube-shaped vessel 12 that defines an enclosed space,generally referred to by the reference numeral 14. The upper, open endof the vessel 12 terminates in a flange 16, which extends generallyperpendicular to the wall of the vessel 12. A closure, or lid 18,preferably rests on the flange 16 to close the upper end of the vessel12. The lid 18 may include a handle 20 to allow the lid 18 to be easilyremoved. Desirably, the lid 18 is capable of being secured to the vessel12 so as to form a fluid tight seal. In the illustrated embodiment, anumber of threaded fasteners, such as eyebolts 22, secure the lid 18 tothe flange portion 16 of the vessel 12. However, other suitable means ofattachment may also be used, such as other mechanical or hydraulicmeans. In addition, other suitable methods of closing the vessel 12 maybe utilized.

[0045] The vessel 12 includes an inlet 24 and outlet 26, each of whichallow fluid communication with the enclosed space 14. The outlet 26 ofthe illustrated embodiment is located at a bottom portion of the vessel12 and is coaxial with a longitudinal axis of the filter 10. However,the outlet 26 may alternatively be positioned in other suitablelocations. For example, the outlet 26 may extend from the side wall ofthe vessel 12, perpendicular to a longitudinal axis of the filter 10,similar to the inlet 24. Alternatively, the bottom end of the vessel 12may terminate in a flange, and a separate outlet member may be connectedthereto, in a manner similar to the lid 18.

[0046] A pressure source 28 is located upstream from the inlet 24 tosupply an unfiltered liquid, or slurry, to the enclosed space 14 of thefilter 10. The pressure source 28 may comprise any type of pump or othermechanism suitable to create a pressurized slurry. Obviously, as one ofskill in the art will recognize, there may be some applications in whichthe slurry may be pre-treated and/or pre-filtered prior to reaching theinlet 24. For example, the illustrated filter apparatus 10 may comprisea portion of a larger filtering apparatus or system.

[0047] A filter assembly, referred to generally by the reference numeral30, is positioned within the enclosed space 14 between the inlet 24 andthe outlet 26. In the illustrated embodiment, the filter assembly 30comprises at least an inner filter 32 and an outer filter 34. Each ofthe inner and outer filters 32 and 34 is substantially annular in shapeand are capable of allowing liquid to pass through while retaining solidparticulate matter. Preferably, each of the filters 32 and 34 iscylindrical in shape to equalize pressure. The space between the innerand outer filters, 32 and 34, defines a collection volume 36 forcollecting solid particulate matter.

[0048] An end cover, such as a substantially circular plate 38 issecured to the upper end of the inner and outer filters, 32 and 34 andis in sealed engagement with the interior surface of the vessel 12.Desirably, the plate 38 is sized, shaped and constructed from a suitablematerial which will maintain a substantially watertight seal with theinterior, cylindrical surface of the vessel 12. Alternatively, othersealing arrangements may be used, such as providing a separate sealmember between the plate 38 and the vessel 12. In another alternative,the inlet 24 may be formed by, or connected to, the lid 18 and the plate38 may be sealed to the vessel 12 at, or near, the flange portion 16. Inone arrangement, this may be accomplished by positioning a peripheralportion of the plate 38 between the flange 16 and the lid 18. Otherconfigurations, apparent to those of skill in the art, which guide theslurry into the collection volume 36 without allowing slurry to pass toa downstream side of the filters 32, 34 may also be used.

[0049] The plate 38 includes several openings 40 that extend axiallythrough the plate 38. The openings 40 direct fluid into the collectionvolume 36 between the inner and outer filters, 32 and 34, respectively.Solid central and peripheral portions of the plate 38 prevent fluid frompassing to the downstream side of the filter assembly 30 without firstentering the collection volume 36.

[0050] Desirably, the inner filter 32 is substantially hollow anddefines an interior space 42 surrounded by the inner filter 32. Theouter filter 34 is spaced from the interior surface of the vessel 12 todefine an exterior space 44 surrounding the outer filter 34. The filter10 additionally includes a transfer assembly 46 configured to provide anoutlet from the interior space 42 to direct fluid from the interiorspace 42 to the exterior space 44. Desirably, the transfer assembly 46is substantially circular and is positioned at the lower end of theinner and outer filters, 32 and 34. The illustrated transfer assembly 46includes a plurality of channels 48 that connect the interior space 42to the exterior space 44, as illustrated in greater detail in the crosssection view of FIG. 3. The transfer assembly 46 also includes a solidend cover, or base portion, 50 closing the lower end of the collectionvolume 36. Optionally, the base portion 50 may be separate from thetransfer assembly 46. In an alternative arrangement, the lower end ofthe interior space 42 may be open and allow fluid to pass directly tothe exterior space 44 without passing through a transfer assembly 46.

[0051]FIG. 2 is an enlarged cross-section view of a portion of thefilter 10 within the circle labeled 2 in FIG. 1. Preferably, the innerfilter 32 includes a rigid filter support, or tube 52, having aplurality of apertures 54 which allow liquid to pass therethrough.Filter media 56 is positioned adjacent to the external surface of theinner filter tube 52 to separate the collection volume 36 from theinterior space 42. The filter media 56 is desirably comprised of asuitable material constructed to allow liquid to pass therethrough butto retain particulate matter. For example, the media may be constructedof paper, cotton, polyester, polypropylene, metal materials (e.g.,stainless steel), or other suitable materials that may be determined byone of skill in the art. The filter media may be of a woven or non-wovenconstruction. The filter media may be constructed to possess one of avariety of minimum particulate size retention capabilities, often givenas a particulate size value in microns, as is known to one of skill inthe art. Desirably, the filter media has a micron rating greater than,or equal to, 0.25 microns. However, as may be determined by one of skillin the art, the minimum particulate size retention of the filter mediamay be altered to suit a desired application. Preferably, the filtermedia is either of a woven construction, or has a density greater thanabout one-half ounce per square yard (or equivalents thereof) in orderto withstand the fluid pressure that may be generated during thefiltering process.

[0052] Similarly, the outer filter 34 includes a filter tube 58 having aplurality of apertures 60. Filter media 62 is positioned adjacent theinterior surface of the outer filter tube 58. Thus, the collectionvolume 36 is preferably defined between the filter media 56 of the innerfilter 32 and the filter media 62 of the outer filter 34. A radialdistance D is defined between the inner filter 32 and the outer filter34. More specifically, in the illustrated embodiment, the distance D isdefined between the inner surface of the outer filter media 62 and theouter surface of the inner filter media 56. Desirably, the distance D isless than about 4 inches. Preferably, the distance D is less than about3 inches and more preferably, the distance D is approximately 2 inches.However, other values of the distance D may be provided depending on theparticular slurry filtering application or desired dryness of theparticulate within the collection volume at the end of a completedfilter cycle. In addition, the facing surfaces of the inner filter media56 and the outer filter media 62 are desirably parallel with oneanother. Such an arrangement assists in equalizing the pressure withinthe collection volume 36. In addition, the parallel relationship betweenthe inner and outer filter media 56, 62 encourages an equal build up ofparticulate cake on each filter media surface. In the illustratedembodiment, the inner and outer filters 32, 34 are annular and, thus,preferably the facing surfaces of the inner filter media 56 and theouter filter media 62 are desirably coaxial with one another.

[0053] The filters 32, 34 also define a length, or elongate dimension ofthe collection volume 36. In the filter 10 of FIG. 1, the elongatedimension of the collection volume 36 corresponds with the verticalheight H of the collection volume 36. In one arrangement, the height Hof the collection volume 36 is desirably between approximately 5 and 60inches, preferably between approximately 12 and 48 inches and morepreferably approximately 30 inches. However, the value of the height Hmay be varied in other arrangements, depending on the particularfiltering application for which the filter 10 will be used. For example,in some applications, the height H of the collection volume 36 may bemuch greater than 60 inches, such as 15 feet or greater, for example.Desirably, the filter tubes 52, 58 are constructed from a suitably rigidmaterial to withstand the pressures generated in a displacementfiltering process. For example, the filter tubes 52, 58 may beconstructed of structural steel, stainless steel, aluminum or otheralloys, plastics or other composites, or combinations thereof, and ispreferably rated for pressures of up to 500 p.s.i., or higher.

[0054] Desirably, the volume of the collection volume 36 is betweenapproximately 0.25 and 5,000 liters and, preferably, betweenapproximately 1 and 500 liters. Additionally, the surfaces of both theinner and outer filter media 56, 62 define a surface area. Desirably,the total surface area of the inner and outer filters 56, 62 is betweenapproximately 200 and 80,000 square inches. Preferably, the totalsurface area of the inner and outer filters 56, 62 is betweenapproximately 200 and 8,000 square inches and more preferably betweenapproximately 200 and 800 square inches. A ratio of the volume tosurface area is desirably about 576 cubic inches per square foot,preferably about 432 cubic inches per square foot and more preferablyabout 288 cubic inches per square foot. However, the volume and surfacearea defined by the filter may be varied to produce a filter apparatussuitable for other filtering applications.

[0055] The filter apparatus 10 is operable to separate solid matter froma solid-liquid mixture, or slurry. The illustrated filter 10 isespecially useful for filtering slurries with a relatively highconcentration of solid matter, such as above about 1000 parts permillion (ppm) or 5,000 ppm, for example, and may be used to filterslurries with a concentration as high as 10,000 to 500,000 ppm. Withreference to FIGS. 1-3, a slurry is introduced to the filter 10 by thepressure source 28. At the beginning of a filtering cycle, the pressuresource 28 supplies the slurry to the filter apparatus 10 at a low tomoderate pressure simply to fill the collection volume 36. The slurryflows into the enclosed space 14 of the filter apparatus 10 through theinlet 24 and into the collection volume 36 through the openings 40 ofthe plate 38, as illustrated by the arrows of FIG. 1.

[0056] Once the collection volume 36 has been substantially filled withslurry, the slurry delivery pressure is gradually increased by thepressure source 28. In response to the incoming slurry, the liquidcomponent of the slurry within the collection volume 36 is forcedthrough either the inner filter 32 or the outer filter 34 while thesolid particulate component is retained within the collection volume 36due to the filter media 56, 62.

[0057] Liquid moving through the inner filter 32 passes through thefilter media 56 and through one of the plurality of apertures 54 of theinner filter tube and into the interior space 42. Liquid moving throughthe outer filter 34 first passes through the filter media 62 and throughone of the plurality of apertures 60 of the outer filter tube 58 andinto the exterior space 44. Liquid filtrate within the interior space 42passes through the channels 48 of the transfer assembly 46 to merge withliquid filtrate in the exterior space 44, as illustrated by the arrowsof FIG. 3. The filtrate then passes from the enclosed space 14 of thevessel 12 through the outlet 26. The outlet 26 may empty into a suitablecontainer or collection system, or may be connected to a drain or othersuitable waste removal system.

[0058] Typically in a displacement filtering process, the pressure ofthe slurry supplied to the filter 10 by the pressure source 28 graduallyincreases throughout the cycle to compensate for the particulate matterbuilding up within the particulate collection volume 36. The particulatematter remaining in the collection volume 36 at the end of a filtercycle, is generally referred to as cake. Preferably, the minimumpressure during the filtering cycle (i.e., not including the initialfilling of the collection volume 36) is approximately 25 p.s.i.Desirably, the pressure increases over the course of the filtering cycleto a maximum of approximately 100 p.s.i. In other applications, themaximum pressure during a filtering cycle may reach approximately 225p.s.i. and, if desired, the maximum pressure may reach up to 1500 p.s.i.or more. The filter apparatus 10 may be constructed to reach even highermaximum pressures during the filtering cycle, depending on the type ofslurry processed or desired dryness of the particulate cake.

[0059] The above-described process is commonly referred to asdisplacement filtering, as liquid is displaced from the collectionvolume 36 thereby leaving substantially only solid particulate matterremaining. At the end of a filtering cycle, substantially the entirecollection volume 36 is desirably filled with particulate. When a 100p.s.i. maximum pressure is reached during the filtering cycle, theparticulate cake is approximately 25-35% dry. When a 225 p.s.i. maximumpressure is reached during the filtering cycle, the particulate cake isapproximately 35-45% dry. The dryness percentages are given in terms ofthe weight of the solid particulate remaining in the particulatecollection volume 36 compared to the weight of both the solid and liquidremaining in the collection volume 36.

[0060] Once the filter cycle is completed, the threaded fasteners 22 areremoved to allow the lid 18 to be removed from the vessel 12. The filterassembly 30 is then capable of being removed through the open, upper endof the vessel 12. The inner filter 32 may also be removed from the outerfilter 34 to allow the particulate cake to be removed from thecollection volume 36. For example, in one arrangement, the inner filter32 may be secured to the transfer assembly 46 to form a firstsubassembly and the outer filter 34 may be secured to the end cover 38to form a second subassembly. The first subassembly may be separatedfrom the second subassembly to expose the collection volume 36 and allowthe particulate cake to be discharged. In other arrangements, the filterassembly 30 may be disassembled in an alternative manner to allow fordischarging of the particulate cake. Once the particulate cake has beenremoved from the collection volume 36, the inner and outer filters 32,34 are cleaned, reassembled and the filter assembly 30 is positionedback within the vessel 12 so that another filter cycle may be carriedout. Thus, preferably the particulate cake may be removed from theannular collection volume through the opening of the vessel 12. Such anarrangement permits particulate cake to be emptied from the filterapparatus 10 quickly and efficiently.

[0061] Advantageously, the illustrated embodiment utilizes a pressurevessel arrangement to structurally withstand the forces generated due tothe relatively high pressures typical of a displacement filteringprocess. Specifically, the vessel 12 is desirably substantiallycylindrical in shape. The vessel 12 defines a substantially continuouscylindrical wall portion and, preferably, a closed end, with theexception of the outlet 26. That is, the wall portion of the vessel 12is desirably a single piece and is annular in shape. More preferably,the vessel 12 is a monolithic structure. Thus, the cylindrical wallportion of the vessel 12 does not require an externally applied force tocounteract the forces produced as a result of the displacement filteringprocess. The forces generated by the filtering process are substantiallyabsorbed by the vessel 12 itself. Desirably, the only external closureforce necessary is to secure the lid 18 to the vessel 12. In theillustrated embodiment, this function is performed by the threadedfasteners 22. Preferably, the vessel 12 and closure arrangement (e.g.,the lid and fasteners 22) are capable of withstanding a pressure withinthe internal space 14 of at least 25 p.s.i. Other means of securing thelid 18 to the vessel 12 may be used, such as other mechanical fastenersor a hydraulic system, as may be determined by one of skill in the art.Additionally, the filter 10 desirably is capable of withstandingoperating pressure differentials of at least 25 p.s.i. A pressuredifferential of the filter 10 may be defined as a difference between thefluid pressure upstream from the filters 32, 34 and the fluid pressuredownstream from the filters 32, 34.

[0062] In addition to withstanding fluid pressure from the filteringprocess, the annular side wall of the vessel 12 desirably is alsoself-supporting. That is, the side wall of the vessel 12 supports itsown weight. In the embodiment of FIGS. 1-3, the filter 10 may besupported by one, or both, of the tubular members defining the outlet 26and the inlet 24, for example. The portion of the annular wall of thevessel 12 between the inlet 24 and the outlet 26 is capable ofsupporting its own weight. In addition, the portion of the annular wallof the vessel 12 between the inlet 24 and the open, upper end of thefilter 10 is also capable of supporting its own weight. Similarly, ifthe filter 10 is mounted in a horizontal arrangement (as illustrated inFIGS. 4 and 5), the annular wall of the vessel 10 desirably is capableof supporting its own weight both in between, and to either side of, theinlet 24 and the outlet 26. Alternatively, one or more supports may beprovided separately from the inlet 24 and the outlet 26, as will bereadily apparent to one of skill in the art.

[0063] In contrast, in a prior art filter press assembly, it isnecessary to provide an external support arrangement for each individualfilter plate, in order to counteract the force of gravity. As describedabove, a large number of filter plates (e.g., up to 100 or more) may beprovided in a single filter press. When the filter press is in a closedposition, a hydraulic closure assembly applies a compressive force toeach end of the filter press to hold the filter plates in contact withone another and create a fluid-tight seal therebetween. The compressiveforce applied by the hydraulic closure assembly also supports the filterplates against the force of gravity. To support the weight of the filterplates when the filter press is in an open position, an elongate supportbeam is typically provided on each side of the filter press assembly andextends the entire length of the filter press. A handle portion on eachside of the filter plates rests on an upper surface of the support beam.Accordingly, the support beam must be strong enough to support theentire weight of all of the filter plates. As a result of the largenumber of individual filter plates that must be supported, the hydraulicclosure assembly and support beam structure are both necessary. Thisresults in a complex and heavy construction that results in the filterpress being expensive to manufacture. By providing a vessel 12 that isself-supporting, the illustrated filter 10 eliminates the need for suchextraneous support.

[0064] Advantageously, the illustrated filter apparatus 10 has a singleseal to be maintained between the vessel 12 and the lid 18. Further, inthe illustrated filter apparatus 10, the area of the lid 18 is desirablysmall, when compared to the interior surface area of the vessel 12,which results in a relatively small closure force being necessary tomaintain a substantially fluid-tight seal between the vessel 12 and thelid 18, because the force tending the separate the lid 18 from thevessel 12 is proportional to the surface area of the lid 18.Accordingly, a large support structure and hydraulic closure system arenot necessary with the present filter apparatus 10.

[0065] In contrast, in a filter press assembly, a seal must bemaintained between each pair of filter plates. Up to 100 or moreindividual filter plates may be provided in a single filter pressassembly. Typically, the plates are square in shape and the seal betweenthem is located along an outer edge of the plates. Therefore, pressuregenerated during the displacement filtering process acts onsubstantially the entire plate. The relatively large surface area of theplates produces a large force tending to separate the plates from oneanother. As a result, a closure system, typically a hydraulic system, isnecessary to hold the series of plates together with a sufficient forceto maintain a seal between the plates. In addition, this force must beapplied to the plates during the entire filter process. Further, thesupport structure, or frame, that supports both the assembly of filterplates and the hydraulic closure system must be rigid enough towithstand the necessary closure force produced by the closure systemwithout substantial deflection, in order to maintain a seal between thefilter plates. Both the closure system and the support structure, orframe, are expensive to manufacture.

[0066] Also, with preferred embodiments of the present filter 10,discharging of particulate cake and cleaning of the filter media may beaccomplished much more quickly than that of a filter press. Because asingle particulate collection volume 36 is desirably provided, theparticulate matter within the collection volume 36 at the end of afilter cycle may be quickly and conveniently discharged. Even ifmultiple collection volumes 36 are provided, desirably, the particulatecake may be discharged through a single opening in the filter 10, whichfacilitates relatively rapid discharge of the particulate cake. Incontrast, with a filter press, the space between each pair of filterplates must be cleaned of particulate matter. Thus, preferredembodiments of the present displacement filter reduce the overallfiltering costs (e.g., labor costs and equipment costs) and permit theadvantages of a displacement filtering process to be cost effective evenin low volume applications.

[0067]FIGS. 4 and 5 illustrate an alternative embodiment of the filterapparatus 10. The filter apparatus 10 of FIGS. 4 and 5 is constructedand operates in a substantially similar manner to the previouslydescribed filter apparatus 10. Therefore, like reference numerals willbe used to describe like components. The filter 10 of FIGS. 4 and 5 isarranged such that the longitudinal axis of the filter 10 is disposedhorizontally.

[0068] The lid 18 is positioned on the open end of the vessel 12, whichis located at the outlet end of the enclosed space 14. The lid 18 may besecured to the vessel 12 by any suitable means, as described in relationto the previous embodiment. With reference to FIG. 5, an optional seal70 engages the open end of the inner filter 32 to substantially preventslurry from entering the interior space 42 without passing through theinner filter 32. The seal 70 may be affixed to the closed end of thevessel 12 or, alternatively, it may be affixed to a closed end portionof the outer filter 34. Desirably, the seal 70 is substantially annularin shape and contacts an end portion of the inner filter 32 to create asubstantially fluid-tight seal therebetween. Alternatively, othersuitable sealing arrangements may be utilized to substantially preventslurry from entering the interior space 42 without passing through theinner filter 32.

[0069] As with the previously described embodiment, slurry is pumpedinto the collection volume 36 through the inlet 24. However, in theembodiment of FIGS. 4 and 5, the inlet 24 opens directly into thecollection volume 36 thereby eliminating the need for the plate 38(FIG. 1) of the previous embodiment. The slurry is filtered as it movesthrough one of the inner filter 32 or the outer filter 34, asillustrated by the arrows of FIG. 4. Liquid filtrate that is passedthrough the inner filter 32 to the interior space 42 passes through thechannels 48 of the transfer assembly 46 to converge with liquid filtratewhich is passed through the outer filter 34 and into the exterior space44. The liquid filtrate then exits the filter apparatus 10 through theoutlet 26.

[0070] The filter apparatus 10 illustrated in FIGS. 4 and 5 includesseveral features which assist in the cleaning of the filter apparatus 10once a filter cycle has been completed. These features desirably includean air purge system, a back flush system and a scraper 57. The air purgesystem primarily comprises an air inlet 72 connected to a pressurizedair source 74. At the end of a filter cycle, pressurized air from theair source 74 is introduced into the enclosed space 14 of the vessel 12to direct any remaining liquid filtrate to the outlet 26.

[0071] The scraper 57 is substantially annular in shape and is attachedto the end of the inner filter 32 opposite the transfer assembly 46. Thescraper 57 extends substantially radially from the inner filter 32 to anouter edge, which is desirably positioned close to, or in contact with,the interior surface of the outer filter 34. Although, the illustratedscraper 57 has a generally convex shape, other suitable configurationsof the scraper 57 may also be used in order to perform the desiredfunction. The scraper 57 is preferably constructed from any suitablyrigid material, such as metal or plastic. However, other suitablematerials may also be used. The scraper 57 may be secured to the innerfilter 32 by any suitable means, such as with threaded fasteners,riveting, adhesives, or the like.

[0072] At the end of a filtering cycle, when the inner filter 32 isremoved from the outer filter 34, the scraper 57 advantageously assistsin the removal of the particulate cake from the collection volume 36.Specifically, the outer filter 34 desirably remains fixed within thevessel 12. The inner filter 32 is desirably removed from the filterapparatus 10 through the open end of the vessel 12 and the scraper 57advantageously moves in a longitudinal direction relative to the outerfilter 34. As the scraper 57 moves relative to the outer filter 34, itremoves at least a substantial portion of the particulate matter thathas accumulated within the collection volume 36 during the filter cycle.This feature reduces the time required to prepare the filter 10 for asubsequent filtering cycle. In another arrangement, the inner filter 32may remain fixed within the vessel 12 and the scraper 57 may be securedto the outer filter 34 to remove particulate matter from the collectionvolume 36 upon removal of the outer filter 34 from the vessel 12. In yetanother arrangement, both the inner and outer filters 32, 34 may remainwithin vessel 12 with only the scraper 57 being removed during cleaningof the filter apparatus 10.

[0073] The back flush system primarily comprises a back flush liquidinlet 76 connected to a back flush liquid source 78. After theparticulate cake is removed from the collection volume 34 (e.g., by thescraper 57), the inner filter 32 is returned to its normal positionwithin the outer filter 34. A back flush liquid, preferably pressurizedwater, is then introduced into the enclosed space 14 of the vessel 12.The back flush liquid travels through the inner and outer filters 32, 34in a direction opposite the normal flow path during a filter cycle(i.e., opposite the direction of the arrows in FIG. 4). Thus, the backflush liquid flows from the interior space 42 and the exterior space 44by passing through the inner filter 32 and outer filter 34,respectively, and into the collection volume 36. The reverse flow of theback flush liquid desirably removes particulate matter remaining on thefilter media of the inner and outer filters 32, 34. A valve assembly 80desirably closes off the pressure source 28 and opens a back flushliquid outlet 82 wherein the back flush liquid and particulate mattermay be evacuated from the filter apparatus 10.

[0074]FIG. 6A is a cross section view of a filter apparatus 10illustrating an alternative arrangement of a filter assembly 30. Boththe inner and outer filters 32, 34 of the filter assembly 30 are annularin shape, however, each of the filters 32, 34 also possess a corrugated,or pleated, arrangement. The corrugated shape is capable of increasingboth the volume of the collection volume 36 and the surface area of theinner and outer filter media 56, 62 within a given size pressure vessel12. This permits more particulate to be collected within the collectionvolume 36, and thus more slurry to be processed, than otherwise possiblewith a similarly sized filter 10 employing a circular cross-sectionfilter assembly 30. The filter assembly may also take on desiredcross-sectional shapes, or sizes, other than those disclosed herein.

[0075]FIG. 6B is a schematic, cross-sectional view of an alternativefilter apparatus 10 utilizing multiple filter assemblies, or filtercells 30. As illustrated in FIG. 6B, a plurality of separate filtercells 30 are positioned concentric with one another within the vessel12. Desirably, each filter cell 30 includes and outer wall 43, whichpreferably encloses the cell 30 and separates the cells 30 from oneanother. In some arrangements, the outer wall 43 may be perforated topermit filtrate to pass through, as is described below. Preferably, eachfilter assembly 30 is substantially similar to the filter assemblies 30described above in relation to FIGS. 1-5. Accordingly, each filterassembly 30 of FIG. 6B includes an inner filter 32 and an outer filter34. A particulate collection volume 36 is defined between each of theinner and outer filters 32, 34. In a manner similar to the embodimentsdescribed above, an interior space 42 is defined between the innerfilter 32 and the outer wall 43 of the filter cell 30. Similarly, anexterior space 44 is defined between the outer filter 34 and the outerwall 43 of the filter cell 30.

[0076] The inner and outer filters 32, 34 may be constructedsubstantially as described above in relation to FIG. 2. Desirably, eachsuch filter includes a perforated support wall and a suitable filtermedia, as described above. In such an arrangement, the interior space 42comprises an outlet space, which communicates with an outlet of thevessel 12, as described above. Alternatively, one or both of the filters32, 34 may additionally include a mechanical squeeze arrangement inwhich a flexible bladder, or membrane, is desirably positioned to theside of the filter media opposite the collection volume 36. An exemplarymechanical squeeze arrangement is described below with reference toFIGS. 7-11. The flexible bladder is arranged to impart a squeezing forceon the particulate cake at the end of the filter cycle to further drythe cake. In the arrangement if FIGS. 6B-6D, the inner filter 32 isillustrated to include a mechanical squeeze arrangement. In such aconfiguration, the interior space 42 desirably comprises a hydraulicfluid cavity and an outlet space (not shown) would be defined betweenthe membrane and the filter media, as is described below with referenceto FIG. 8. Hydraulic fluid within the cavity may then be pressurized toexpand the flexible bladder and impart a squeezing force on theparticulate cake.

[0077] In operation, the filter apparatus 10 of FIG. 6B functions in amanner similar to the embodiments described above. Slurry is introducedinto the particulate collection volume 36 of each filter cell 30, thepressure is increased, and the liquid component of the slurry movesthrough the filters 32, 34 while the solid particulate is retainedwithin the collection volumes 36. The liquid component of the slurry isforced through the inner and outer filters 32, 34 and into the interiorand exterior spaces 42, 44, respectively, assuming that no mechanicalsqueeze arrangement is present. The interior and exterior spaces 42, 44are in fluid communication with one or more outlets (not shown) of thefilter apparatus 10. The outlets may be in the form of a transferassembly 46 (FIGS. 1-5) interconnecting the interior space 42 with theexterior space 44 in a manner similar to the embodiments describedabove, for example. Other suitable arrangements for supplying the slurryto the particulate collection volumes 36 and evacuating the filteredliquid component from the vessel 12 may also be used.

[0078] Providing multiple filter assemblies 30 increases the totalvolume of the particulate collection volume 36 of the filter apparatus10 while maintaining a desirable distance between the inner and outerfilters 32, 34 and, therefore, increases the amount of slurry that canbe processed during a single filtering cycle. As will be apparent by oneof skill in the art, the number of filter assemblies provided may bevaried to suit a particular application.

[0079]FIG. 6C is a schematic, cross-sectional view of yet another filterassembly arrangement. The filter assembly of FIG. 6C includes aplurality of linear filter cells 30 that extend generally in a radialdirection from the center of the filter apparatus 10. As in the filterassembly 10 of FIG. 6B, each filter cell 30 includes an outer wall 43that encloses the filter cell 30 and separates the cells 30 from oneanother. Due at least in part to the cells 30 not being in contact withone another, the outer wall 43 may be perforated to permit filtrate topass through the outer wall 43 and into the space between the cells 30.Of course, if a mechanical squeeze arrangement is incorporated into aparticular cell 30, the outer wall adjacent the membrane, or bladder,would not be perforated so as to define a hydraulic cavity to retain thehydraulic fluid. Further, each filter cell 30 includes a first filter 32and a second filter 34, which cooperate to define a particulatecollection volume 36 between them. Thus, the first and second filters32, 34 function as the inner and outer filters in the embodimentsdescribed above.

[0080] In operation, slurry is introduced into the filter assembly 30.The liquid component of the slurry is forced through both the firstfilter 32 and the second filter 34 of each filter cell 30 and into theinterior and exterior spaces 44. As in the previous embodiments, thesolid component of the slurry is retained within the particulatecollection volume 36. Similar to the embodiment of FIG. 6B, thisarrangement also increases the volume of the particulate collectionvolume 36 within the filter apparatus 10 and, thus, the volume of slurrythat may be processed in a single filtering cycle.

[0081]FIG. 6D is a schematic, cross-sectional view of still anotherarrangement of a filter apparatus 10. The filter 10 of FIG. 6D includesa plurality of individual, linear filter cells 30, each having a firstfilter 32 and a second filter 34. The first and second filters 32, 34define a particulate collection volume 36 within each of the individualfilter cells 30. Again, the first and second filters 32, 34 of thefilter assembly 30 of FIG. 6D function in a similar manner to the innerand outer filters of the embodiments described above with relation toFIGS. 1-5. If desired, a mechanical squeeze arrangement may also beincorporated into the filter cells 30 of FIG. 6D.

[0082] As illustrated in FIG. 6D, several lengths of filter cells 30 areprovided to substantially fill the available space within the vessel 12.Alternatively, the filters 35 may be of a single length (e.g., a similarlength to the shortest illustrated filter cells 30) and simply arrangedto most efficiently utilize the space within the vessel 12. In anotherarrangement, the individual filter cells 30 may be connected with oneanother to form a single particulate collection volume 36. For example,each filter cell 30 may be connected to the filter 35 adjacent to it,thereby connecting the particulate collection volumes 36 defined by eachof the filters 35.

[0083] As in the arrangements of FIGS. 6A-6C, slurry is introduced intothe particulate collection volume 36 within each of the filter cells 30of FIG. 6D. The liquid component of the slurry is forced through thefirst and second filters 32, 34 and into the interior and exteriorspaces 42, 44, respectively. From the interior and exterior spaces 42,44, the liquid component is evacuated from the vessel 12 in a suitablemanner, such as those described above.

[0084] As will be readily determined by one of skill in the art, thefilter assemblies 30 described above in relation to FIGS. 6A-6D aremerely exemplary arrangements. Accordingly, the filter assembly 30 maybe modified from those illustrated to suit a particular application. Inaddition, various suitable methods for introducing the slurry to theparticulate collection volume 36 may be utilized, including, but notlimited to, those described above in relation to FIGS. 1-5. Furthermore,each of the illustrated filter assembly 30 arrangements may utilizeother features described in relation to FIGS. 1-5, as well as theautomatic features described below, as may determined by one of skill inthe art. Advantageously, any of the embodiments illustrated in FIGS.6A-6D may include a scraper to permit automatic removal of particulatecake from within the particulate collection volume, as will be readilydetermined by one of skill in the art.

[0085]FIG. 7 illustrates an automatic embodiment of a filter apparatus100. The automatic filter 100 is constructed in a similar manner to theembodiments described above with reference to FIGS. 1-5 and operates tofilter particulate matter from a slurry in a similar manner. However,the filter 100 advantageously includes features that permit the filter100 to automatically discharge at least a substantial portion of theparticulate cake and prepare the filter media for further use. Thus, theautomatic filter 100 is more efficient and requires less operator timefor cake discharge and cleaning in comparison with previously describedembodiments and, as a result, is less expensive to operate.

[0086] The illustrated filter 100 includes a cylindrically shaped vessel102 which is closed at its upper end and open at its lower end. Thelower end of the vessel 102 terminates in a flange 104, which extends inan outward direction, generally transverse to the cylindrical wall ofthe vessel 102. The vessel 102 defines an enclosed space, generallyidentified by the reference numeral 106. As in the embodiments above,the vessel 102 includes an inlet 108 in an outlet 110, which permitliquid to enter and exit the enclosed space 106 of the vessel 102,respectively.

[0087] A filter assembly 112 is positioned within the enclosed space 106between the inlet 108 and the outlet 110. The filter assembly 112includes an inner filter 114 surrounded by an outer filter 116. In theillustrated embodiment both the inner filter 114 and the outer filter116 are substantially cylindrical in shape, however, other suitableshapes may also be used. An interior space 118 is defined within theinner filter 114 and an exterior space 120 is defined between the outerfilter 116 and the interior surface of the vessel 102. The inner filter114 and the outer filter 116 define an annular collection volume 122between them.

[0088] An end cover 124 is attached to the upper end of the inner filter114 to close off the upper end of the interior space 118. Similar to theembodiments above, a transfer assembly 126 is attached to the lower endof the inner filter 114. A plurality of channels 128 connect theinterior space 118 and the exterior space 120 to permit fluid to passfrom the interior space 118 to the exterior space 120. An end cover, orbase portion 130, of the transfer assembly 126 closes the lower end ofthe collection volume 122. Optionally, the end cover 130 may be aseparate piece from the transfer assembly 126. An inner filter base 132is connected to the lower end of the transfer assembly 126 and closesoff the open, lower end of the vessel 102. The inner filter base 132includes a seal surface 134 that engages the interior surface of thevessel 102 to create a substantially fluid-tight seal therebetween.Optionally, a seal member, such as an O-ring, may be used to create aseal between the inner filter base 132 and the vessel 102. Othersuitable arrangements to prevent fluid from entering or exiting theenclosed space 106, except through the inlet 108 or outlet 110 mayalternatively be employed.

[0089] Desirably, the outer filter 116 includes a flange 136 attached toits upper end. An upper end of the flange 136 extends generallytransversely to the outer filter 116 and engages the interior surface ofthe vessel 102 at a position below the inlet 108. The flange 136 closesthe upper end of the exterior space 120 and desirably creates afluid-tight seal between the outer filter 116 and the interior surfaceof the vessel 102. Alternatively, a seal member may be positionedbetween the flange 136 and the vessel 102 to provide a seal between theouter filter 116 and the vessel 102.

[0090] In a similar manner to the embodiments described above, a slurryis introduced into the enclosed space 106 of the vessel 102 through theinlet 108. The slurry is prevented from entering either the interiorspace 118 or the exterior space 120 by the end cover 124 and flange 136,respectively, and therefore enters a passage 138 defined between the endcover 124 and the flange 136. The slurry passes through the passage 138into the collection volume 122. Once the collection volume 122 issubstantially filled, the supply pressure of the slurry is graduallyincreased, as described above in relation to the embodiment of FIGS.1-5. In response to this increased pressure, a liquid component of theslurry is forced through the inner and outer filters 114, 116 while thesolid, particulate component is retained within the collection volume122. Liquid passing through the inner filter 114 enters the interiorspace 118 and passes through the channels 128 of the transfer assembly126 and into the exterior space 120. Liquid moving through the outerfilter 116 moves directly into the exterior space 120. Liquid in theexterior space 120 then exits from filter 100 through the outlet 110.The filter cycle desirably continues until the collection volume 122 issubstantially filled with solid particulate matter, or cake.

[0091] With additional reference to FIGS. 8 and 9, the filter 100desirably includes a mechanical squeeze arrangement 140 for applying asqueezing pressure to the particulate cake to further remove liquid fromthe collection volume 122 at the end of a filtering cycle. In theillustrated embodiment, the mechanical squeeze arrangement 140 includesa flexible bladder 141 and a support member 142 positioned within theannular inner filter 114. The bladder 141 and support member 142 definea fluid chamber 143 between them. A squeeze pressure source 144 isconnected for fluid communication with the chamber 143 by a suitabledelivery channel 145 (FIG. 7). The pressure source 144 is configured toprovide a pressurized flow of fluid to the chamber 143 to expand thebladder 141 and thus squeeze the particulate cake. The relative positionof the squeeze arrangement 140, namely the bladder 141 and supportmember 142, is illustrated in phantom in FIG. 7.

[0092] The support member 142 is substantially cylindrical in shape andis positioned generally concentrically within the inner filter 114.Desirably, the support member 142 extends substantially the entirelength of the inner filter 114. The support member 142 is preferablyconstructed from a suitably rigid material to withstand the pressuresgenerated by the squeeze arrangement 140. For example, the supportmember 142 may be made from any type of suitable steel, alloy, plastic,or composite material. Other suitable materials, or combination ofmaterials may also be used.

[0093] The support member 142 includes a grooved flange 146 extendinggenerally transverse to the cylindrical wall of the support member 142.The flange 146 is desirably positioned proximate the lower end of theinner filter 114. The bladder 141 is also cylindrical in shape andsurrounds the support member 142. A lower end of the bladder 141 isreceived by the grooved flange 146 and may be secured in place by anysuitable means, such as mechanical fasteners, adhesives, or the like.Although not shown, an upper end of the bladder 141 may be secured tothe support member 142 in a similar manner. Alternatively, othersuitable methods of securing the bladder 141 to the support member 142,or otherwise creating a chamber 143 between them, may also be used.

[0094] An outer surface of the bladder 141 desirably includes aplurality of raised portions, or projections 147. In the illustratedembodiment, the projections 147 are substantially cylindrical in shapeand extend radially outward from the outer surface of the bladder 141.The projections 147 space the inner filter media 115 from thecylindrical wall of the bladder 141. Liquid passing through the innerfilter media 115 is able to flow downward in the space defined betweenthe projections 147 (illustrated by the arrows in FIG. 9) and into thechannels 128 of the transfer assembly. Thus, when a mechanical squeezeassembly 140 is employed, the interior space 118 within the inner filter114 is primarily defined by the space between the projections 147 and issubstantially annular, rather than cylindrical as in the embodiments ofFIGS. 1-6.

[0095] With additional reference to FIG. 7, the delivery channel 145 forsupplying pressurized fluid to the chamber 143, desirably passes throughthe internal passage 180 of the screw 142. A transfer pipe 148 defines aportion of the delivery channel 145 between the internal passage 180 andthe chamber 143 (FIG. 8). Desirably, the chamber is substantially sealedwith the exception of the delivery channel 145. This may be accomplishedby the grooved flange arrangement, as described above, or by othersuitable constructions or methods.

[0096] At the completion of a filter cycle, the squeeze pressure source144 is desirably automatically activated to supply a pressurized fluidto the chamber 143. Due to the rigid nature of the support member 142,the flexible bladder 141 advantageously expands in response to thepressurized fluid being introduced into the chamber 143 (as illustratedin phantom in FIG. 8). The bladder 141 applies a squeezing pressure tothe particulate cake against the resistance of the rigid, outer filter116, thereby reducing the volume of the particulate volume 122. Thismechanical squeezing of the particulate cake removes a substantialportion of the liquid otherwise remaining within the particulate cakeafter the displacement filter process. For example, a filter 100utilizing a mechanical squeeze arrangement 140 may typically produce aparticulate cake that is 50-70% dry in a filter cycle time equal to orless than a displacement filtering process without a mechanical squeezestep.

[0097] Desirably, the mechanical squeeze arrangement 140 utilizes arelatively incompressible fluid, such as hydraulic fluid or water andthe squeeze pressure source 144 comprises a positive displacement pump.However, a pneumatic squeeze arrangement or other suitable fluids and/orpressure sources may also be used. Desirably, the squeeze pressuresource 144 is capable of creating a pressure within the chamber 143 ofbetween approximately 10 and 15,000 psi. Preferably, the squeezepressure source 144 is capable of creating a pressure within the chamber143 of between approximately 25 and 10,000 psi and more preferablyapproximately 300 psi. Additionally, the mechanical squeeze arrangement140 may be configured for use with any of the filter apparatusembodiments disclosed herein.

[0098] Other techniques may be employed along with, or alternative to,the mechanical squeeze arrangement 140. For example, a vacuum may beapplied during the filtering process to further aid in removing liquidfrom the particulate collection volume 122, resulting in a dryerparticulate cake C at the end of the filter cycle. Similarly, heat maybe applied to the particulate collection volume 122 to aid inevaporation of the liquid therein and, thus, increase the dryness of thecake C. Additionally, an air purge (or other gaseous medium) system maybe provided to introduce air (or gas) to the particulate collectionvolume 122 after the filter cycle, to further assist drying of theparticulate cake C. As will be apparent to one of skill in the art, anyof the above-described cake drying techniques or systems may be usedalong, or in conjunction with one another, to achieve a desired drynesspercentage of the particulate cake C.

[0099] As mentioned above, the filter 100 also desirably includesfeatures which permit cleaning and preparation of the filter 100 forfurther use automatically at the end of a filter cycle. Desirably, thefilter 100 includes a filter closure assembly 150, or drive, which isoperable to move the inner filter 114 with respect to the outer filter116 and vessel 102 along a longitudinal axis A of the filter 100 topermit particulate to be discharged from the collection volume 122. Inthe illustrated embodiment, the filter closure assembly 150 includes athreaded screw 152 rotatably coupled to the inner filter 114. The screw152 extends in an upward direction from the inner filter 114 through anaperture 154 in the closed end of the vessel 102. In the illustratedembodiment, the aperture 154 is defined by an internally threaded collar156. External threads of the screw 152 mate with the internal threads ofthe collar 156 such that rotation of the screw 152 causes it to moveaxially with respect to the vessel 102 and thereby move the inner filter114 along the longitudinal axis A. Desirably, the screw 152 is able torotate with respect to the inner filter 114 so that rotation of thescrew 152 only results in axial movement of the inner filter 114 withoutcausing rotation of the inner filter 114. A drive device, or motor 158,is desirably connected to the screw 152 to selectively impart rotationalmotion thereon. Alternatively, other suitable drive arrangements mayalso be used, such as a telescoping rod arrangement as described belowwith reference to FIG. 12, for example.

[0100] The filter 100 also desirably includes an upper scraper 160attached to the inner filter 114 at a position near the upper end of thecollection volume 122. Desirably, the upper scraper 160 is substantiallyannular in shape and includes a peripheral edge which is spaced at leastslightly from the interior surface of the outer filter 116 in order topermit slurry to pass from the passage 138, past the upper scraper 160and into the collection volume 122. Desirably, the filter assembly 112also includes a lower scraper 162 connected to a lower end of the outerfilter 116 such that it is positioned at a lower end of the collectionvolume 122. The lower scraper 162 is also desirably annular in shape andincludes a plurality of passages 164 extending axially through thescraper 162. The inner peripheral edge of the lower scraper 162 may bepositioned close to or touching the exterior surface of the inner filter114. Thus, particulate matter, or cake, within the collection volume 122may be discharged through the passages 164 in the lower scraper 162.Alternatively, the upper scraper 160 may include one or more passages,similar to the passages 164 of the lower scraper 162, to permit slurryto pass into the collection volume 122 and the outer peripheral edge maybe positioned close to or touching the outer filter 116.

[0101] Advantageously, the filter 100 also includes a filter spray washarrangement for spraying a fluid, such as water or other type ofcleaner, onto the surfaces of the inner and outer filters 114, 116. Thespray wash arrangement includes an upper spray assembly 166 and a lowerspray assembly 168. The upper spray assembly 166 includes one or morespray nozzles 170 attached to and spaced around the circumference of theend cover 124. Thus, the upper nozzles 170 are fixed for movement withthe inner filter 114. Each of the upper nozzles 170 include an outlet172 arranged to spray liquid in a radial direction toward the outerfilter 116. The upper spray nozzles 170 are interconnected by an upperfeed channel 174 defined at least in part by a tube 176.

[0102] Similarly, the lower spray assembly 168 includes one or morelower nozzles 178 which are connected to, and arranged around thecircumference of, the interior surface of the vessel 102. Each of thelower nozzles 178 includes an outlet 180 which is arranged to spray awash liquid in a radial directly toward the inner filter 114. Thenozzles 178 are interconnected by a lower nozzle feed channel 182defined at least in part by a tube 184. Advantageously, both the upperand lower spray nozzles 170, 178 are arranged such that their respectiveoutlets 172, 180 are covered while slurry is being filtered. Thisfeature prevents particulate in the slurry from clogging or otherwisedamaging the outlets 172, 180. As illustrated, the outlets 172 of theupper spray nozzles 170 are covered by an inner surface 183, or cover,of the flange portion 136 of the outer filter 116. Similarly, theoutlets 180 of the lower spray nozzles 178 are covered by an outersurface 185, or cover, of the base portion 130 of the inner filter 114.Alternatively, other suitable arrangements may be employed to cover, orotherwise protect, the outlets 172, 180 while the filter 100 is in aclosed position and in a filtering mode.

[0103] Both the upper spray assembly 166 and the lower spray assembly168 are connected to a wash liquid pressure source 186. The pressuresource 186 supplies a pressurized wash liquid, such as water, awater/detergent mixture, an acid wash, or other suitable cleaning fluid,at a pressure sufficient to remove particulate matter from the inner andouter filters 114, 116. An upper delivery channel 188 connects thepressure source 186 to the upper nozzle feed channel 174. Desirably, theupper delivery channel 188 passes through an internal passage 190defined by the hollow interior of the screw 152. A transfer pipe 192defines a portion of the upper delivery channel extending from theinternal passage 190 to the upper nozzle feed channel 174. Desirably,the transfer pipe 192 terminates at one of the upper nozzles 170 wherean aperture 194 defines a portion of the upper delivery channel 188 thatopens into the upper nozzle feed channel 174. A lower delivery channel196 connects the pressure source 186 to the lower spray assembly 168. Anaperture 198 passes through the vessel 102 and one of the lower nozzles178 to connect the lower delivery channel 196 to the lower nozzle feedchannel 182.

[0104] Desirably, the filter apparatus 100 includes a controller 199connected to one or more components or systems of the filter 100 forselectively controlling at least a portion of the operational sequenceof the filter 100. Preferably, as illustrated in FIG. 7, the controller199 is connected to the motor 158 to selectively actuate the motor 158to control the movement of the inner filter 114 between the open andclosed positions. Although not shown, the controller 199 may also beconnected to the squeeze pressure source 144 and the wash liquidpressure source 186 to control operation of those components, as will bedescribed below. The controller 199 may comprise any type of suitablecontroller, including a dedicated controller or a controller configuredto process software code, for example, and desirably comprises a memorycomponent. Alternatively, the controller 199 may comprise a plurality ofindividual controllers connected to specific components of the filter100. The controller 199 may also include any number of suitable sensors,such as position or pressure sensors, to assist in the operationalcontrol of the filter 100, as may be determined by one of skill in theart.

[0105] As described above, at the end of a filter cycle, the collectionvolume 122 is substantially filled with particulate matter. During thefilter cycle, the filter 100 is in a closed position substantially asillustrated in FIG. 7. With reference to FIG. 10, once a filter cyclehas been completed, the filter closure assembly 150 operates to open thefilter 100 so that the particulate matter within the collection volume122 may be discharged. Specifically, the motor 158 operates to rotatethe screw 152 which results in the inner filter 114 lowering withrespect to the vessel 102 (and the outer filter 116) along thelongitudinal axis A of the filter 100, as demonstrated by the arrow ODof FIG. 10. Although the filter 100 is substantially symmetrical aboutthe longitudinal axis A, other non-symmetrical filter shapes may also beemployed while still defining a longitudinal axis A. That is, thelongitudinal axis A is a line that extends generally lengthwise alongthe filter apparatus and symmetry is not required for a specificembodiment to define a longitudinal axis A.

[0106] As the inner filter 114 lowers with respect to the outer filter116 the upper scraper 160 and lower scraper 162 assist in removingparticulate cake C from the collection volume 122. A lower surface ofthe upper scraper 160 engages the particulate cake C and forces itdownward through the passages 164 of the lower scraper. The particulatecake is then assisted by gravity out of the filter 100 through the openlower end of the vessel 102. Advantageously, an outer peripheral edge ofthe upper scraper 160 assists in removing particulate cake C from on orproximate the interior surface of the outer filter 116. Similarly, aninner peripheral surface of the lower scraper 162 assists in removingparticulate cake on or proximate to the exterior surface of the innerfilter 114. In this manner, a substantial portion of the particulatecake C may be automatically removed from the collection volume 122.

[0107] Once the particulate cake C has been substantially dischargedfrom the collection volume 122, the motor 158 reverses to turn the screw152 in an opposite direction thereby moving the inner filter 114 in anupward direction, returning it to a position within the vessel 102.Desirably, the inner filter 114 is returned substantially to its closedpositioned, as illustrated in FIG. 7. Preferably, the inner filter 114is moved upward to at least a position wherein the outlets 172 of theupper nozzles 170 are substantially aligned with the uppermost portionof the outer filter 116.

[0108] With reference to FIG. 11, the filter 100 desirably begins afilter wash mode after the particulate cake C has been discharge by thepreceding process. Desirably, a catch basin 200 is moved to a positionunder the filter 100. The catch basin 200 is preferably sized and shapedto contact the flange 104 of the vessel 102 about its entirecircumference. In an alternative arrangement, the catch basin 200 mayremain in a fixed position under the filter 100, or may be unitarilyformed with the vessel 102. In such an arrangement, preferably, a valve201 is provided in a bottom surface of the catch basin 200 toselectively permit particulate cake C to be discharge from the basin 200and, in another mode, retain wash liquid so that it passes to the outlet202.

[0109] The wash liquid pressure source 186 is activated to supply apressurized wash liquid to the upper and lower spray assemblies 166, 168through the upper and lower delivery channels 188, 196, respectively.Pressurized water is discharged from the upper nozzles 170 of the upperspray assembly 166 toward the interior surface of the outer filter 116.Preferably, the upper nozzles 170 and nozzle outlets 172 are arrangedsuch that the wash liquid contacts substantially the entirecircumference of the outer filter 116. Similarly, wash liquid is sprayedfrom the outlets 180 of the lower spray nozzles 178 toward the exteriorsurface of the inner filter 114. Preferably, substantially the entirecircumference of the inner filter 114 is contacted by wash liquidemitted from the lower nozzles 178. Desirably, the wash liquid pressuresource 186 supplies wash liquid at a pressure sufficient tosubstantially remove particulate matter from the filters 114, 116.Desirably, the pressure source 186 provides wash liquid at a pressurefrom approximately 5 psi to 10,000 psi. Preferably, the pressure source186 provides wash liquid at a pressure from approximately 10 psi to5,000 psi and, more preferably, approximately 1200 psi.

[0110] Once the pressure source 186 has been activated and wash liquidis being sprayed from the upper and lower spray assemblies 166, 168, thefilter closure assembly 150 operates to lower the inner filter 114, asindicated by the arrow O_(W) in FIG. 11. As the inner filter 114 movesdownward, the wash liquid being sprayed from the upper spray assembly166 advantageously removes substantially any particulate matterremaining on the outer filter 116. The wash liquid and particulate thenmove downward through the gap between the upper scraper 160 and theouter filter 116. Alternatively, the upper scraper 160 may be positionedabove the spray nozzles 170.

[0111] The wash liquid and particulate continue to move downward throughthe passages 164 of the lower scraper 162 and into the catch basin 200.Likewise, the wash liquid being sprayed from the lower spray assembly168 washes substantially any remaining particulate from the inner filter114 and the wash liquid and particulate move downwardly into the catchbasin 200. From the catch basin, the wash liquid and particulate aredesirably evacuated from the catch basin through an outlet 202 and backinto the system via return line 204. It is then readmitted to the filter100 along with other unfiltered slurry by slurry pressure source 205through supply line 207. Alternatively, the wash liquid may be directedto a drain line 209.

[0112]FIG. 12 illustrates an alternative embodiment comprised of a pairof filters 100 connected to a common supply channel at least partiallydefined by a tube 210, which selectively supplies slurry to either, orboth, of the filters 100 a, 100 b. The supply line 210 splits into afirst branch 212 which supplies slurry to the first filter 100 a and asecond branch 214 which supplies slurry to the second filter 100 b. Afirst valve 216 and a second valve 218 operate to control the supply ofslurry to the first branch 212 and second branch 214, respectively.Although two filters 100 are illustrated, any suitable number may beprovided.

[0113] The filters 100 a, 100 b of FIG. 12 are arranged such that theinner filter 114 remains stationary and the filter closure assembly 150operates to lift the vessel 102 upward with respect to the inner filterassembly 114. The filter closure assembly 150 of filters 100 a, 100 bcomprises a telescoping rod arrangement 220. The rod may be hydraulic orpneumatic and is supplied with a fluid from a fluid supply source 222through first and second supply lines 224, 226, respectively. Theindividual filters 100 a, 100 b preferably operate in a similar mannerto those filter embodiments previously described. The filters 100 a, 100b are preferably automatic, similar to the embodiment of FIGS. 7-11, butmay alternatively include any desirable combination of automaticfeatures described above.

[0114] With reference to FIG. 13, the vessel 102 and the inner filter114 are selectively secured, and preferably sealed, to one another by asegmented flange and ring assembly, as is known in the art.Specifically, the inner filter base 132 of filters 100 a, 100 b includesa flange 228, which is sized and shaped to mate with flange 104 ofvessel 102. Preferably, at least the flange 104 includes a plurality ofinterrupted areas spaced around its circumference. A clamp member 232,or clamp ring, operates to exert a closing pressure on the flanges 104,228 thus squeezing them together. Desirably, the clamp ring 232 includesa plurality of segments around its circumference, which are sized andshaped to pass through the interrupted areas of the flange 104. Thus,when the segments of the clamp ring 232 are aligned with the interruptedareas of the flange 104, the vessel 102 may be lifted upward and awayfrom the inner filter 114 to open the filter assembly 100 a, 100 b.Desirably, the flange 104 and/or the clamp ring 232 includes a camsurface 234 such that rotation of the clamp ring 232 increases thesqueezing force on the flanges 104, 228. Desirably, a seal member 230,such as an O-ring, is positioned between the two mating surfaces of theflange 230 and flange 104 to create a seal therebetween. In theillustrated embodiment, the seal member 230 is retained within a groovedefined by the flange 104 of the vessel 102. However, the seal member230 may alternatively be affixed to the flange 228 of the inner filterbase 132. Alternatively, other suitable sealing arrangements may also beused.

[0115]FIG. 14 illustrates an alternative filter arrangement wherein,similar to the embodiment of FIG. 12, the vessel 102 and outer filter116 are moved in an upward direction with respect to the inner filter114 to allow particulate to be removed from the collection volume 122.In the arrangement of FIG. 14, the respective vessels 102 of the pair offilters 100 a, 100 b are interconnected by the filter vessel liftassembly 150. The lift assembly 150 includes a lever arm 240 to whichthe respective vessels 102 of the filters 100 a, 100 b are rotatablycoupled on opposing ends. The lever arm 240 is rotatably coupled to avertical support 242 at approximately the mid-point of the lever arm 240such that rotation of the lever arm 240 about the axis M causes thevessel 102 of one filter 100 a, 100 b to move in an upward direction,while the vessel 102 of the opposing filter 100 a, 100 b moves in adownward direction. Thus, rotation of the lever arm 240 closes onefilter (100 b in FIG. 12), while opening the other filter (100 a in FIG.12). Alternatively, the lift assembly 150 may be arranged to permitindependent movement of the vessels 102.

[0116] In the illustrated embodiment, the filters 100 a, 100 b aremounted to a support structure, such as a platform, or bench 244.Preferably, the horizontal portion of the bench 244 includes one or morepassages 246 which permit particulate cake to empty from the filters 100a, 100 b and pass into a receptacle, such as a bin or cart 248,positioned underneath the bench 244. Optionally, a chute 250 may directthe particulate cake into the cart 248.

[0117] In this embodiment, filter 100 a is illustrated in a filteringmode and filter 100 b is illustrated in a cleaning mode. When filter 100a is substantially filled with particulate matter, the lever 240 will berotated about the axis M such that filter 100 a is opened and filter 100b is closed. Particulate may then be emptied from filter 100 a whilefiltering of slurry takes place in filter 100 b. Thus, if connected to asingle slurry source, the pair of filters 100 a, 100 b are arranged suchthat slurry can be continuously filtered.

[0118]FIG. 15 illustrates an embodiment of a filter 100 which utilizesan alternative lifting arrangement 150. The lifting arrangement 150includes a frame 252 surrounding the filter 100. The frame 252 isdesirably square in horizontal cross-section and includes four verticalsupport posts 254 (only three shown), with one post 254 being positionedat each corner. With additional reference to FIG. 16, a drive gear 256is connected to the vessel 102 of filter 100 and is driven by a motor258. Teeth 260 formed on the drive gear 256 mesh with teeth 262 of thecorresponding post 254. With additional reference to FIG. 17, an idlerwheel 264 is attached to the vessel 102 at each of the other three post245. A smooth surface 266 of the idler wheel 264 rolls against a smoothsurface 268 of the post 245 and assists in maintaining a verticalorientation of the vessel 102. Thus, the motor 258 rotates the drivegear 256 to move the vessel 102 (and outer filter) axially with respectto the inner filter 114, as illustrated by the arrow of FIG. 13, to movethe filter between an open and a closed position. Alternatively, morethan one drive gear 256 may be provided.

[0119] Although the present invention has been described in the contextof several preferred embodiments, modifications and rearrangements ofthe illustrated embodiments may be made without departing from thespirit and scope of the invention. For example, but without limitation,both the vessel and the filter assembly may take on other forms orshapes. Additionally, any or all of the automated features to assist inthe filtering or cleaning process may be incorporated on any of thefilter embodiments disclosed herein, or on other suitable variations ofthe filter apparatus. Further, the sequence of operation of the filterapparatus may be varied from the order described herein. Othermodifications obvious to one of skill in the art may also be made.Accordingly, the scope of the present invention is to be defined only bythe appended claims.

What is claimed is:
 1. A filter apparatus for dewatering a slurry,comprising: a pressure vessel having a first end, a second end, and aone-piece, annular side wall portion, said side wall portion having aninternal surface generally defining an internal space, one of said firstend and said second end defining an opening to permit access to saidinternal space; a closure sized and shaped for selectively closing saidopening, said pressure vessel and said closure configured to withstand apressure of at least 25 psi in said internal space when said opening isclosed; an annular inner filter defining an external surface and aninternal cavity, said internal cavity at least partially defining afirst outlet space, a substantial portion of said inner filter whichforms said external surface comprising a first filter media; an outerfilter surrounding said inner filter and defining an internal surfacefacing said external surface, a substantial portion of said outer filterwhich forms said internal surface comprising a second filter media, saidfirst filter media and said second filter media comprising one of awoven material and a material configured to retain a particulate sizegreater than or equal to about 0.25 microns, said first and secondfilter media defining an annular particulate collection volumetherebetween, said outer filter and said internal surface of said vesseldefining a second outlet space therebetween; an inlet communicating withsaid internal space, said inlet configured to direct a slurry into saidparticulate collection volume before passing through either of saidinner filter and said outer filter; an outlet communicating with saidinternal space, said outlet being in fluid communication with said firstoutlet space and said second outlet space; a pressure source upstreamfrom said inlet, wherein pressure from said pressure source isdirectable through said inlet to force a fluid component of a slurrywithin said particulate collection volume through said inner filter tosaid first outlet space and through said outer filter to said secondoutlet space, said first and second filter media retaining a solidcomponent of a slurry within said particulate collection volume to forma particulate cake, and said opening being sized and shaped to permit aparticulate cake within said particulate collection volume to be removedthrough said opening.
 2. The filter apparatus of claim 1, additionallycomprising a scraper sized and shaped to extend substantially from saidfirst filter media to said second filter media, said scraper beingmovable from a first end of said particulate collection volume toward asecond end of said particulate collection volume to remove particulatecake from said particulate collection volume.
 3. The filter apparatus ofclaim 2, wherein said scraper generally conforms to a cross-sectionalshape of said particulate collection volume.
 4. The filter apparatus ofclaim 1, wherein said inner filter and said outer filter are movableaxially with respect to one another to facilitate said particulate cakebeing removed from said particulate collection volume.
 5. The filterapparatus of claim 4, additionally comprising a scraper sized and shapedto extend substantially from said first filter media to said secondfilter media, said scraper being movable from a first end of saidparticulate collection volume toward a second end of said particulatecollection volume to remove particulate cake from said particulatecollection volume, wherein said scraper is attached to one of said innerfilter and said outer filter.
 6. The filter apparatus of claim 1,wherein said closure comprises a lid, said lid being secured to saidvessel by a plurality of threaded fasteners.
 7. The filter apparatus ofclaim 1, wherein said outer filter has a length defining an axis and amaximum cross-sectional dimension of said outer filter perpendicular tosaid axis is less than said length of said outer filter.
 8. The filterapparatus of claim 1, wherein each of said external surface of saidinner filter and said internal surface of said outer filter aresubstantially cylindrical, said particulate cake forming on saidcylindrical surfaces.
 9. The filter apparatus of claim 1, wherein saidinner and outer filters have a complementary corrugated shape.
 10. Thefilter apparatus of claim 1, further comprising a slurry, wherein aconcentration of a solid component of said slurry is greater than orequal to 1,000 parts per million.
 11. The filter apparatus of claim 1,further comprising a slurry, wherein a concentration of a solidcomponent of said slurry is greater than or equal to 5,000 parts permillion.
 12. A filter apparatus for dewatering a slurry, comprising: apressure vessel having a first end, a second end, and a one-piece,annular side wall portion, said side wall portion having an internalsurface generally defining an internal space, one of said first end andsaid second end defining an opening to permit access to said internalspace; a closure sized and shaped for selectively closing said opening;an annular inner filter defining an external surface and an internalcavity, said internal cavity at least partially defining a first outletspace, a substantial portion of said inner filter which forms saidexternal surface comprising a first filter media; an outer filtersurrounding said inner filter and defining an internal surface facingsaid external surface, said internal surface and said external surfacebeing substantially parallel, a substantial portion of said outer filterwhich forms said internal surface comprising a second filter media, saidfirst filter media and said second filter media comprising one of awoven material and a material configured to retain a particulate sizegreater than or equal to about 0.25 microns, said first and secondfilter media defining an annular particulate collection volumetherebetween, said outer filter and said internal surface of said vesseldefining a second outlet space therebetween; an inlet communicating withsaid internal space, said inlet configured to direct a slurry into saidparticulate collection volume before passing through either of saidinner filter and said outer filter; an outlet communicating with saidinternal space, said outlet being in fluid communication with said firstoutlet space and said second outlet space; a pressure source upstreamfrom said inlet, wherein pressure from said pressure source isdirectable through said inlet to force a fluid component of a slurrywithin said particulate collection volume through said inner filter tosaid first outlet space and through said outer filter to said secondoutlet space, said first and second filter media retaining a solidcomponent of a slurry within said particulate collection volume to forma particulate cake, and said opening being sized and shaped to permit aparticulate cake within said particulate collection volume to be removedthrough said opening; wherein said pressure source produces a firstfluid pressure upstream from said particulate collection volume and asecond fluid pressure downstream from said particulate collectionvolume, the difference between said first fluid pressure and said secondfluid pressure defining a pressure differential, said filter apparatusconfigured to withstand operating pressure differentials of at least 25psi.
 13. The filter apparatus of claim 12, additionally comprising ascraper sized and shaped to extend substantially from said first filtermedia to said second filter media, said scraper being movable from afirst end of said particulate collection volume toward a second end ofsaid particulate collection volume to remove particulate cake from saidparticulate collection volume.
 14. The filter apparatus of claim 13,wherein said scraper generally conforms to a cross-sectional shape ofsaid particulate collection volume.
 15. The filter apparatus of claim12, wherein said inner filter and said outer filter are movable axiallywith respect to one another to facilitate said particulate cake beingremoved from said particulate collection volume.
 16. The filterapparatus of claim 15, additionally comprising a scraper sized andshaped to extend substantially from said first filter media to saidsecond filter media, said scraper being movable from a first end of saidparticulate collection volume toward a second end of said particulatecollection volume to remove particulate cake from said particulatecollection volume, wherein said scraper is attached to one of said innerfilter and said outer filter.
 17. The filter apparatus of claim 12,wherein said closure comprises a lid, said lid being secured to saidvessel by a plurality of threaded fasteners.
 18. The filter apparatus ofclaim 12, wherein said outer filter has a length defining an axis and amaximum cross-sectional dimension of said outer filter perpendicular tosaid axis is less than said length of said outer filter.
 19. The filterapparatus of claim 12, wherein each of said external surface of saidinner filter and said internal surface of said outer filter aresubstantially cylindrical, said particulate cake forming on saidcylindrical surfaces.
 20. The filter apparatus of claim 12, wherein saidinner and outer filters have a complementary corrugated shape.
 21. Thefilter apparatus of claim 12, further comprising a slurry, wherein aconcentration of a solid component of said slurry is greater than orequal to 1,000 parts per million.
 22. The filter apparatus of claim 12,further comprising a slurry, wherein a concentration of a solidcomponent of said slurry is greater than or equal to 5,000 parts permillion.
 23. A filter apparatus for filtering a slurry, comprising: apressure vessel having a first end, a second end and an annular wall, asupport portion configured to secure said pressure vessel in a location,said wall of said pressure vessel including a first portion between saidsupport and one of said first end and said second end of said vessel,said first portion of said wall being capable of providing sufficientresistance to gravity acting on said first portion of said wall tomaintain the structural integrity of said first portion of said wall; anannular inner filter defining an external surface and an internalcavity, said internal cavity at least partially defining a first outletspace, a substantial portion of said inner filter which forms saidexternal surface comprising a first filter media; an outer filtersurrounding said inner filter and defining an internal surface facingsaid external surface, a substantial portion of said outer filter whichforms said internal surface comprising a second filter media, said firstfilter media and said second filter media comprising one of a wovenmaterial and a material configured to retain a particulate size greaterthan or equal to about 0.25 microns, said first and second filter mediadefining an annular particulate collection volume therebetween, saidouter filter and said internal surface of said vessel defining a secondoutlet space therebetween; an inlet communicating with said internalspace, said inlet directing said slurry into said particulate collectionvolume before passing through either of said inner filter and said outerfilter; an outlet communicating with said internal space, said outletbeing in fluid communication with said first outlet space and saidsecond outlet space; a pressure source upstream from said inlet, whereinpressure from said pressure source is directable through said inlet toforce a fluid component of a slurry within said particulate collectionvolume through said inner filter to said first outlet space and throughsaid outer filter to said second outlet space, said first and secondfilter media retaining a solid component of a slurry within saidparticulate collection volume to form a particulate cake.
 24. The filterapparatus of claim 23, additionally comprising a second support portionconfigured to secure said pressure vessel in a location, said wall ofsaid pressure vessel including a second portion between said firstsupport and said second support, said second portion of said wall beingcapable of providing sufficient resistance to gravity acting on saidsecond portion of said wall to maintain the structural integrity of saidsecond portion of said wall.
 25. The filter apparatus of claim 23,wherein said inner filter and said outer filter comprise a filterassembly having a first end and a second, said filter apparatus furthercomprising a first filter assembly support and a second filter assemblysupport, said filter assembly including a portion between said firstfilter assembly support and said second filter assembly support, saidportion of said filter assembly being capable of providing sufficientresistance to gravity acting on said filter assembly to maintain thestructural integrity of said filter assembly.
 26. The filter apparatusof claim 25, additionally comprising a second support portion configuredto secure said pressure vessel in a location, said wall of said pressurevessel including a second portion between said first support and saidsecond support, said second portion of said wall being capable ofproviding sufficient resistance to gravity acting on said second portionof said wall to maintain the structural integrity of said second portionof said wall.
 27. The filter apparatus of claim 23, wherein saidpressure vessel defines a longitudinal axis, said longitudinal axisbeing arranged vertically when said pressure vessel is secured to saidsurface.
 28. The filter apparatus of claim 23, wherein said pressurevessel defines a longitudinal axis, said longitudinal axis beingarranged horizontally when said pressure vessel is secured to saidsurface.
 29. The filter apparatus of claim 23, additionally comprising ascraper sized and shaped to extend substantially from said first filtermedia to said second filter media, said scraper being movable from afirst end of said particulate collection volume toward a second end ofsaid particulate collection volume to remove particulate cake from saidparticulate collection volume.
 30. The filter apparatus of claim 29,wherein said scraper generally conforms to a cross-sectional shape ofsaid particulate collection volume.
 31. The filter apparatus of claim23, wherein said inner filter and said outer filter are movable axiallywith respect to one another to facilitate said particulate cake beingremoved from said particulate collection volume.
 32. The filterapparatus of claim 31, additionally comprising a scraper sized andshaped to extend substantially from said first filter media to saidsecond filter media, said scraper being movable from a first end of saidparticulate collection volume toward a second end of said particulatecollection volume to remove particulate cake from said particulatecollection volume, wherein said scraper is attached to one of said innerfilter and said outer filter.
 33. The filter apparatus of claim 23,wherein one of said first end and said second end define an opening topermit access to said internal space, said filter apparatus additionallycomprising a closure sized and shaped for selectively closing saidopening.
 34. The filter apparatus of claim 33, wherein said closurecomprises a lid, said lid being secured to said vessel by a plurality ofthreaded fasteners.
 35. The filter apparatus of claim 23, wherein saidouter filter has a length defining an axis and a maximum cross-sectionaldimension of said outer filter perpendicular to said axis is less thansaid length of said outer filter.
 36. The filter apparatus of claim 23,wherein each of said external surface of said inner filter and saidinternal surface of said outer filter are substantially cylindrical,said particulate cake forming on said cylindrical surfaces.
 37. Thefilter apparatus of claim 23, wherein said inner and outer filters havea complementary corrugated shape.
 38. The filter apparatus of claim 23,further comprising a slurry, wherein a concentration of a solidcomponent of said slurry is greater than or equal to 1,000 parts permillion.
 39. The filter apparatus of claim 23, further comprising aslurry, wherein a concentration of a solid component of said slurry isgreater than or equal to 5,000 parts per million.
 40. A filter apparatusfor dewatering a slurry, comprising: a pressure vessel having a firstend, a second end, and a one-piece, annular side wall portion, said sidewall portion having an internal surface generally defining an internalspace, one of said first end and said second end defining an opening topermit access to said internal space; a closure sized and shaped forselectively closing said opening, said pressure vessel and said closureconfigured to withstand a pressure of at least 25 psi in said internalspace when said opening is closed; at least one filter assemblycomprising a first filter and a second filter, said first filterdefining a first surface and at least partially defining a first outletspace, a substantial portion of said first filter which forms said firstsurface comprising a first filter media, said second filter defining asecond surface facing said first surface, said second filter at leastpartially defining a second outlet space, a substantial portion of saidsecond filter which forms said second surface comprising a second filtermedia, said first and second filter media defining a particulatecollection volume therebetween; an inlet communicating with saidinternal space, said inlet configured to direct a slurry into saidparticulate collection volume before passing through either of saidfirst filter and said second filter; an outlet communicating with saidinternal space, said outlet being in fluid communication with said firstoutlet space and said second outlet space; a pressure source upstreamfrom said inlet, wherein pressure from said pressure source isdirectable through said inlet to force a fluid component of a slurrywithin said particulate collection volume through said first filter tosaid first outlet space and through said second filter to said secondoutlet space, said first and second filter media retaining a solidcomponent of a slurry within said particulate collection volume to forma particulate cake, and said opening being sized and shaped to permit aparticulate cake within said particulate collection volume to be removedthrough said opening; a scraper sized and shaped to extend substantiallyfrom said first filter media to said second filter media, said scraperbeing movable from a first end of said particulate collection volumetoward a second end of said particulate collection volume to removeparticulate cake from said particulate collection volume.
 41. The filterapparatus of claim 40, said first filter media and said second filtermedia comprising one of a woven material and a material configured toretain a particulate size greater than or equal to about 0.25 microns.42. The filter apparatus of claim 40, wherein said at least one filterassembly comprises a plurality of filter assemblies.
 43. The filterapparatus of claim 40, wherein said scraper generally conforms to across-sectional shape of said particulate collection volume.
 44. Thefilter apparatus of claim 40, wherein said first filter and said secondfilter are movable axially with respect to one another to facilitatesaid particulate cake being removed from said particulate collectionvolume.
 45. The filter apparatus of claim 40, wherein said closurecomprises a lid, said lid being secured to said vessel by a plurality ofthreaded fasteners.
 46. The filter apparatus of claim 40, wherein saidfirst and second filters have a complementary corrugated shape.
 47. Thefilter apparatus of claim 40, further comprising a slurry, wherein aconcentration of a solid component of said slurry is greater than orequal to 1,000 parts per million.
 48. The filter apparatus of claim 40,further comprising a slurry, wherein a concentration of a solidcomponent of said slurry is greater than or equal to 5,000 parts permillion.
 49. A filter apparatus for dewatering a slurry, comprising: apressure vessel having a first end, a second end, and a one-piece,annular side wall portion, said side wall portion having an internalsurface generally defining an internal space, one of said first end andsaid second end defining an opening to permit access to said internalspace; a closure sized and shaped for selectively closing said opening;at least one filter assembly comprising a first filter and a secondfilter, said first filter defining a first surface and at leastpartially defining a first outlet space, a substantial portion of saidfirst filter which forms said first surface comprising a first filtermedia, said second filter defining a second surface facing said firstsurface and at least partially defining a second outlet space, saidfirst surface and said second surface being substantially parallel, asubstantial portion of said second filter which forms said secondsurface comprising a second filter media, said first and second filtermedia defining a particulate collection volume therebetween; an inletcommunicating with said internal space, said inlet configured to directa slurry into said particulate collection volume before passing througheither of said first filter and said second filter; an outletcommunicating with said internal space, said outlet being in fluidcommunication with said first outlet space and said second outlet space;a pressure source upstream from said inlet, wherein pressure from saidpressure source is directable through said inlet to force a fluidcomponent of a slurry within said particulate collection volume throughsaid first filter to said first outlet space and through said secondfilter to said second outlet space, said first and second filter mediaretaining a solid component of a slurry within said particulatecollection volume to form a particulate cake, and said opening beingsized and shaped to permit a particulate cake within said particulatecollection volume to be removed through said opening; wherein saidpressure source produces a first fluid pressure upstream from saidparticulate collection volume and a second fluid pressure downstreamfrom said particulate collection volume, the difference between saidfirst fluid pressure and said second fluid pressure defining a pressuredifferential, said filter apparatus configured to withstand operatingpressure differentials of at least 25 psi; and a scraper sized andshaped to extend substantially from said first filter media to saidsecond filter media, said scraper being movable from a first end of saidparticulate collection volume toward a second end of said particulatecollection volume to remove particulate cake from said particulatecollection volume.
 50. The filter apparatus of claim 49, said firstfilter media and said second filter media comprising one of a wovenmaterial and material configured to retain a particulate size greaterthan or equal to about 0.25 microns.
 51. The filter apparatus of claim49, wherein said at least one filter assembly comprises a plurality offilter assemblies.
 52. The filter apparatus of claim 49, wherein saidscraper generally conforms to a cross-sectional shape of saidparticulate collection volume.
 53. The filter apparatus of claim 49,wherein said first filter and said second filter are movable axiallywith respect to one another to facilitate said particulate cake beingremoved from said particulate collection volume.
 54. The filterapparatus of claim 49, wherein said closure comprises a lid, said lidbeing secured to said vessel by a plurality of threaded fasteners. 55.The filter apparatus of claim 49, wherein said first and second filtershave a complementary corrugated shape.
 56. The filter apparatus of claim49, further comprising a slurry, wherein a concentration of a solidcomponent of said slurry is greater than or equal to 1,000 parts permillion.
 57. The filter apparatus of claim 49, further comprising aslurry, wherein a concentration of a solid component of said slurry isgreater than or equal to 5,000 parts per million.
 58. A filter apparatusfor filtering a slurry, comprising: a pressure vessel having a firstend, a second end and an annular wall, a support portion configured tosecure said pressure vessel in a location, said wall of said pressurevessel including a first portion between said support and one of saidfirst end and said second end of said vessel, said first portion of saidwall being capable of providing sufficient resistance to gravity actingon said first portion of said wall to maintain the structural integrityof said first portion of said wall; at least one filter assemblycomprising a first filter and a second filter, said first filterdefining a first surface and at least partially defining a first outletspace, a substantial portion of said first filter which forms said firstsurface comprising a first filter media, said second filter defining asecond surface facing said first surface and at least partially defininga second outlet space, a substantial portion of said second filter whichforms said second surface comprising a second filter media, said firstand second filter media defining a particulate collection volumetherebetween; an inlet communicating with said internal space, saidinlet directing said slurry into said particulate collection volumebefore passing through either of said first filter and said secondfilter; an outlet communicating with said internal space, said outletbeing in fluid communication with said first outlet space and saidsecond outlet space; a pressure source upstream from said inlet, whereinpressure from said pressure source is directable through said inlet toforce a fluid component of a slurry within said particulate collectionvolume through said first filter to said first outlet space and throughsaid second filter to said second outlet space, said first and secondfilter media retaining a solid component of a slurry within saidparticulate collection volume to form a particulate cake; and a scrapersized and shaped to extend substantially from said first filter media tosaid second filter media, said scraper being movable from a first end ofsaid particulate collection volume toward a second end of saidparticulate collection volume to remove particulate cake from saidparticulate collection volume.
 59. The filter apparatus of claim 58,additionally comprising a second support portion configured to securesaid pressure vessel in a location, said wall of said pressure vesselincluding a second portion between said first support and said secondsupport, said second portion of said wall being capable of providingsufficient resistance to gravity acting on said second portion of saidwall to maintain the structural integrity of said second portion of saidwall.
 60. The filter apparatus of claim 59, wherein said at least onefilter assembly comprises a first end and a second, said filterapparatus further comprising a first filter assembly support and asecond filter assembly support, said filter assembly including a portionbetween said first filter assembly support and said second filterassembly support, said portion of said filter assembly being capable ofproviding sufficient resistance to gravity acting on said filterassembly to maintain the structural integrity of said filter assembly.61. The filter apparatus of claim 60, additionally comprising a secondsupport portion configured to secure said pressure vessel in a location,said wall of said pressure vessel including a second portion betweensaid first support and said second support, said second portion of saidwall being capable of providing sufficient resistance to gravity actingon said second portion of said wall to maintain the structural integrityof said second portion of said wall.
 62. The filter apparatus of claim58, wherein said pressure vessel defines a longitudinal axis, saidlongitudinal axis being arranged vertically when said pressure vessel issecured to said surface.
 63. The filter apparatus of claim 58, whereinsaid pressure vessel defines a longitudinal axis, said longitudinal axisbeing arranged horizontally when said pressure vessel is secured to saidsurface.
 64. The filter apparatus of claim 58, said first filter mediaand said second filter media comprising one of a woven material and amaterial configured to retain a particulate size greater than or equalto about 0.25 microns.
 65. The filter apparatus of claim 58, whereinsaid scraper generally conforms to a cross-sectional shape of saidparticulate collection volume.
 66. The filter apparatus of claim 58,wherein said first filter and said second filter are movable axiallywith respect to one another to facilitate said particulate cake beingremoved from said particulate collection volume.
 67. The filterapparatus of claim 58, wherein one of said first end and said second enddefine an opening to permit access to said internal space, said filterapparatus additionally comprising a closure sized and shaped forselectively closing said opening.
 68. The filter apparatus of claim 58,wherein said first and second filters have a complementary corrugatedshape.
 69. The filter apparatus of claim 58, further comprising aslurry, wherein a concentration of a solid component of said slurry isgreater than or equal to 1,000 parts per million.
 70. The filterapparatus of claim 58, further comprising a slurry, wherein aconcentration of a solid component of said slurry is greater than orequal to 5,000 parts per million.
 71. A method of separating particulatematter from a slurry, comprising; providing a filter apparatuscomprising a pressure vessel having a first end, a second end, and asubstantially cylindrical wall portion defining a longitudinal axis ofsaid filter apparatus, said pressure vessel defining an internal space;providing a first annular filter and a second annular filter within saidinternal space, said second annular filter surrounding said firstannular filter, said first annular filter and said second annular filterdefining an annular particulate collection volume therebetween,directing a flow of said slurry into said particulate collection volumeunder sufficient pressure to force fluid to flow in a substantiallyradial direction through said first annular filter and through saidsecond annular filter and any of said particulate matter blocking afiltering surface of said first annular filter and said second annularfilter to substantially fill said particulate collection volume withparticulate.
 72. The method of claim 71, additionally comprisingmaintaining said pressurized flow until said particulate collectionvolume is substantially filled with said particulate matter.
 73. Themethod of claim 71, wherein said pressure is at least 25 psi.
 74. Themethod of claim 71, wherein a concentration of particulate matter insaid slurry is greater than 1000 parts per million.
 75. A filterapparatus, comprising: a pressure vessel having a first end, a secondend, and a cylindrical wall portion extending between said first andsecond ends, said pressure vessel defining an internal space, one ofsaid first end and said second end comprising an opening to permitaccess to said internal space; a closure sized and shaped forselectively closing said opening; at least one filter assembly withinsaid internal space, said at least one filter assembly defining a firstfilter surface and a second filter surface facing said first filtersurface, said first filter surface and said second filter surface atleast partially defining a particulate collection volume therebetween;an inlet directing a slurry into said particulate collection volumebefore said fluid passes through either of said first filter surface andsaid second filter surface; at least one outlet located downstream fromat least one of said first filter surface and said second filtersurface; a pressure source upstream from said inlet, wherein pressurefrom said pressure source is directed through said inlet to force afluid component of said slurry within said collection volume throughsaid first filter surface and said second filter surface to said atleast one outlet, said first filter surface and said second filtersurface retaining a solid component of said slurry within saidparticulate collection volume to form a particulate cake, said openingbeing sized and shaped such that a particulate cake formed in saidparticulate collection volume is removable through said opening.
 76. Theapparatus of claim 75, wherein said at least one filter assemblycomprises a plurality of arm portions extending from a longitudinal axisof said pressure vessel, each of said plurality of arm portions defininga portion of said first filter surface and said second filter surface.77. The apparatus of claim 75, wherein said at least one filter assemblycomprises a plurality of substantially linear filters arranged withinsaid pressure vessel.
 78. The apparatus of claim 75, wherein said atleast one filter assembly comprises an inner annular filter and an outerfilter surrounding said inner filter, said inner filter defining saidfirst filter surface and said outer filter defining said second filtersurface.
 79. The apparatus of claim 78, wherein said at least one filterassembly comprises a first filter assembly and a second filter assemblypositioned coaxial to one another with said pressure vessel.
 80. Theapparatus of claim 75, wherein said at least one outlet comprises afirst outlet and a second outlet, said first outlet located downstreamfrom said first surface and said second outlet located downstream fromsaid second surface.
 81. The apparatus of claim 75, wherein said firstand said second outlets converge.
 82. The apparatus of claim 75, whereineach of said first filter surface and said second filter surface have acorrugated shape.
 83. The apparatus of claim 75, wherein said pressuresource provides at least 25 p.s.i. of pressure.
 84. A filter apparatus,comprising: an annular inner filter defining an internal cavity; anouter filter surrounding said inner filter, said inner filter and saidouter filter defining an annular particulate collection volume when saidfilter apparatus is in a closed position, said inner filter and saidouter filter being movable axially with respect to one another to definean open position wherein particulate may be emptied from said filterapparatus; an outlet located downstream from said particulate collectionvolume; an inlet directing fluid into said particulate collection volumebefore said fluid passes through either of said inner filter and saidouter filter; and a drive having a portion which exerts force on atleast one of said inner filter and said outer filter to move said filterapparatus between said open position and said closed position.
 85. Thefilter apparatus of claim 84, additionally comprising at least oneliquid sprayer having at least one spray nozzle which is capable ofspraying a liquid toward at least one of said inner filter and saidouter filter
 86. The filter apparatus of claim 84, additionallycomprising at least one liquid sprayer carried by one of said innerfilter and said outer filter, said liquid spray apparatus comprising atleast one spray nozzle for spraying a liquid toward the other of saidinner filter and said outer filter.
 87. The filter apparatus of claim86, wherein said at least one liquid spray apparatus comprises a firstspray apparatus and a second spray apparatus, said first spray apparatusbeing carried by said inner filter and arranged to spray a liquid towardsaid outer filter and said second spray apparatus being carried by saidouter filter and arranged to spray a liquid toward said inner filter.88. The filter apparatus of claim 86, wherein said other of said innerfilter and said outer filter comprises a cover, substantially sealingsaid at least one spray nozzle when said filter apparatus is in a closedposition.
 89. The filter apparatus of claim 84, additionally comprisingat least one annular scraper having a portion which is sized and shapedsuch that axial movement of said inner filter and said outer filter withrespect to one another causes said scraper to at least substantiallyremove particulate from said particulate collection volume.
 90. Thefilter apparatus of claim 84, additionally comprising at least oneannular scraper carried by one of said inner filter and said outerfilter, said scraper being sized and shaped such that axial movement ofsaid inner filter and said outer filter with respect to one anothercauses said scraper to at least substantially remove particulate fromsaid particulate collection volume.
 91. The filter apparatus of claim90, wherein said at least one annular scraper comprises a first scraperattached to said inner filter at a first end portion of said particulatecollection volume and a second scraper attached to said outer filter ata second end portion of said particulate collection volume, said secondscraper including a plurality of passages permitting particulate to passtherethrough during said axial movement of said inner filter and saidouter filter with respect to each other.
 92. A method of separatingparticulate matter from a slurry, comprising: providing a filterapparatus comprising an annular inner filter, an outer filtersurrounding said inner filter, said inner filter and said outer filterdefining an annular particulate collection volume between them, saidfilter apparatus further comprising an outlet located downstream fromsaid particulate collection volume and an inlet directing fluid intosaid particulate collection volume before said fluid passes througheither of said inner filter and said outer filter; initiating afiltering cycle comprising directing a flow of said slurry into saidparticulate collection volume under sufficient pressure to force fluidthrough said inner and outer filters and any of said particulate matterblocking a filtering surface of said inner and outer filters tosubstantially fill said particulate collection volume; initiating adrive to move said inner filter and said outer filter axially withrespect to one another upon completion of said filtering cycle to emptyparticulate from said particulate collection volume.
 93. The method ofclaim 92, said filter further comprising a controller, said methodfurther comprising initiating said drive with said controller.
 94. Themethod of claim 92, further comprising providing at least one annularscraper sized and shaped such that axial movement of said inner filterand said outer filter with respect to one another causes said scraper toat least substantially remove particulate from said particulatecollection volume.
 95. The method of claim 92, further comprisingspraying at least one of said inner and outer filters with a wash liquidduring said axial movement of said inner filter and said outer filterwith respect to one another.
 96. A filter apparatus, comprising: anannular inner filter defining an internal cavity; an outer filtersurrounding said inner filter, said inner filter and said outer filterdefining an annular particulate collection volume when said filterapparatus is in a closed position, said inner filter and said outerfilter being movable axially with respect to one another to define anopen position wherein particulate may be emptied from said filterapparatus; an outlet located downstream from said particulate collectionvolume; an inlet directing fluid into said particulate collection volumebefore said fluid passes through either of said inner filter and saidouter filter; and means for moving said filter apparatus between saidopen position and said closed position.